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Journal of Computer Assisted Tomography - Current Issue

Journal of Computer Assisted Tomography - Current Issue
  1. Automated Segmentation of Head Computed Tomography Images Using FSL
    imageObjective The aim of this study was to investigate the use of one magnetic resonance image-processing tool, FSL, in its ability to perform automated segmentation of computed tomographic images of the brain. Methods Head computed tomography (CT) images were brain extracted and segmented using the FSL tools BET and FAST, respectively. The products of segmentation were analyzed by histogram. The impact of image intensity inhomogeneity correction was investigated using simulated bias fields, 14 routine head CT scans, and selected illustrative clinical cases. Results FSL FAST performs direct segmentation of head CT images, permitting quantitation of gray and white matter densities and volumes, achieving a more complete segmentation than masking methods. “Bias field correction” reduced the covariance of image signal intensities of the total brain and gray matter images (P < 0.01). Correction is larger when the effects of beam hardening and radiation scatter are larger, resulting in improved segmentation. Conclusions FSL FAST enables direct segmentation of head CT images.



  2. Intravoxel Incoherent Motion Diffusion-Weighted Imaging Versus Dynamic Contrast-Enhanced Magnetic Resonance Imaging: Comparison of the Diagnostic Performance of Perfusion-Related Parameters in Breast
    imageObjective The aim of this study was to investigate the diagnostic performance of the perfusion-related parameters of intravoxel incoherent motion (IVIM) imaging for breast lesions, compared with dynamic contrast-enhanced magnetic resonance imaging (DCE MRI). Methods Fifty-nine patients with both IVIM imaging and subsequent DCE MRI were enrolled. Perfusion-related parameters of IVIM imaging (perfusion fraction, f; pseudo–diffusion coefficient, D*), as well as model-based and model-free parameters of DCE MRI, were measured. Receiver operating characteristic curve analysis and correlations between the IVIM and DCE MRI parameters were performed. Results Thirty-one malignant and 35 benign lesions were pathologically proved. The area under the receiver operating characteristic curves (AUC) of D* plus f (AUCf+D*) was 0.834. The combined AUC of all model-based DCE MRI parameters (AUCmodel-based) was 0.904. The combined AUC of all model-free DCE MRI parameters (AUCmodel-free) was 0.876. AUCf+D* had no significant difference with either AUCmodel-based or AUCmodel-free. No significant correlation was found between f or D* and DCE-derived parameters. Conclusions Intravoxel incoherent motion imaging has the same value in differentiating malignant and benign breast lesions, compared with DCE MRI, in terms of perfusion-related parameters.



  3. Liver Imaging Reporting and Data System: Discordance Between Computed Tomography and Gadoxetate-Enhanced Magnetic Resonance Imaging for Detection of Hepatocellular Carcinoma Major Features
    imagePurpose The goal of this study was to compare agreement between computed tomography (CT) and magnetic resonance imaging (MRI) in the evaluation of the major Liver Imaging Reporting and Data System (LI-RADS) features used in assessment of hepatocellular carcinoma: arterial phase hyperenhancement (APHE), portal venous phase washout (WO), capsule appearance (capsule), and largest diameter (diameter). Methods Patients with liver protocol CT and gadoxetate-enhanced MRI within 1 month of each other and at least 1 discrete untreated liver lesion were included. Two readers independently reviewed hepatic arterial phase and portal venous phase of each lesion on both CT and MRI, presented at random. The APHE, WO, capsule, and diameter were assessed for each lesion on CT and MRI. The LI-RADS category was assigned based on the recorded major features. Interobserver agreements between the readers for both imaging modalities and for each of the major features were assessed using κ statistics. Agreement between CT and MRI for each reader and for each feature was assessed using κ statistics. Agreement was interpreted based on κ as follows: 0.20 or less, slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80, substantial agreement; and 0.81 to 1.00, almost perfect agreement. Intraclass correlation coefficient was used to assess concordance of diameter measurements. Results There were 42 patients (mean age, 62.2 ± 7.0 years; 33 men [78.6%]) with 50 lesions. On CT, the interobserver agreement between the readers was almost perfect for APHE (κ = 0.85), WO (κ = 0.83), and capsule (κ = 0.86). On MRI, the interobserver agreement between the readers was almost perfect for APHE (κ = 0.86) and WO (κ = 0.83) and moderate for capsule (κ = 0.59). Intraclass correlation coefficient for diameter measurement was 0.99 for CT and 0.98 for MRI. For reader 1, the agreement between CT and MRI was fair for APHE (κ = 0.39) and capsule (κ = 0.26) and moderate for WO (κ = 0.49). For reader 2, the agreement between CT and MRI was moderate for APHE (κ = 0.43) and capsule (κ = 0.43) and fair (κ = 0.38) for WO. Agreement between readers for final LI-RADS category was substantial for CT (κ = 0.79) and moderate for MRI (κ = 0.60). Agreement for final LI-RADS categories between MRI and CT was fair for both reader 1 (κ = 0.33) and reader 2 (κ = 0.39). Conclusions Interobserver agreement for the major LI-RADS features varies from moderate to almost perfect, for both CT and MRI. However, the agreement between CT and MRI for each of the major LI-RADS features is poor, ranging from fair to moderate. This poor agreement contributes to substantial differences between final LI-RADS category assigned on CT versus MRI.



  4. Predicting Neoadjuvant Chemotherapy in Nonconcentric Shrinkage Pattern of Breast Cancer Using 1H-Magnetic Resonance Spectroscopic Imaging
    imageObjective The aim of this study was to explore the response to neoadjuvant chemotherapy (NAC) in nonconcentric shrinkage pattern of breast cancer (BC) patients using 1H–magnetic resonance spectroscopy. Methods Twenty-five BC patients were the study cohort. All patients received AT-based regimen as first-line treatment. Tumor response to chemotherapy was evaluated after the second and fourth cycles using magnetic resonance imaging and magnetic resonance spectroscopy. Final histopathology following surgery after 4 to 8 cycles of NAC served as a reference. Changes in total choline integral* (tCho) and tumor size in response versus nonresponse groups were compared using the 2-way Mann-Whitney nonparametric test. Receiver operating characteristic (ROC) analyses were undertaken, and the area under the ROC curve compared among them. Results 1H–magnetic resonance spectroscopy revealed a negative tCho integral* in 6 cases at the first follow-up and 14 cases at the second follow-up. Based on pathology (Miller-Payne system), there were 16 cases of response, and 9 cases of nonresponse. The tCho integral* was significantly different between the response and nonresponse groups at the second follow-up (P = 0.027). The tumor size changes were not significantly different in the response and nonresponse groups at the second follow-up study (P > 0.05). The comparison of ROC curves among the change in tCho integral* and tumor size at baseline and both follow-ups revealed the maximum area under the ROC curve of the change in tCho integral* to be 0.747 at the second follow-up, sensitivity to be 93.75%, and positive predictive value to be 78.9%. Conclusions In nonconcentric shrinkage pattern after NAC of BC, when tumor size is difficult to reflect the response, tCho integral* reduction may be a predictive marker.



  5. Transient Segmental Enhancement of Pyogenic Liver Abscess: A Comparison Between Contrast-Enhanced Ultrasound and Computed Tomography
    imageObjective This study aimed to investigate the correlation between the transient segmental enhancement (TSE) of liver abscesses on contrast-enhanced ultrasound (CEUS) imaging and contrast-enhanced computed tomography (CT) scans. Methods In total, 42 abscesses in 38 patients were evaluated with real-time CEUS and contrast-enhanced CT imaging. The CT imaging and CEUS examinations were performed within one to 2 days of each other in all cases. The initial reports of the observations of TSE on CEUS scans were correlated later with the findings of TSE on contrast-enhanced CT images. Contrast-enhanced CT was used as the reference standard to evaluate the presence of TSE. Relationships between the 2 groups were analyzed using the χ2 test. P < 0.05 was considered to be statistically significant. Results In 16 patients, 16 typical TSE signs were shown by CEUS. Meanwhile, enhanced CT imaging showed 18 typical signs of TSE in 17 patients. We identified 38 patients with hepatic abscesses proven by needle aspiration (10 patients) or image-guided biopsy (28 patients). Ten patients had hepatobiliary cholelithiasis, 5 had diabetes mellitus type 2, and 2 had gastric cancer, whereas no evidence of underlying hepatobiliary or gastrointestinal diseases was found in the other 21 patients. Considering that enhanced CT is the reference standard for the diagnosis of hepatic abscesses, the sensitivity of CEUS in showing TSE was 89%, and the specificity was 100%. The χ2 test indicated that CEUS and enhanced CT were significantly correlated for detection of hepatic perfusion disorders (P < 0.05). Conclusions The appearance of TSE in liver abscess was reliably detected by CEUS, which correlated well with the enhanced CT images (P < 0.05).


  6. Planar Bone Scan Versus Computerized Tomography in Staging Locally Advanced Breast Cancer in Asymptomatic Patients: Does Bone Scan Change Patient Management Over Computerized Tomography?
    imageAim The Royal College of Radiologists guidelines from 2013 recommend that contrast-enhanced computerized tomography of chest, abdomen and pelvis (CT TAP) for breast cancer patients with suspected metastasis could obviate the need for bone scan in asymptomatic patients. The purpose of this study was to perform a head-to-head comparison of bone scan and CT scan in locally advanced breast cancer patients. The aim of this study was to evaluate the utility of planar bone scan in changing the stage or management of locally advanced breast cancer patients. Methods Between June 2006 and January 2016, 156 breast cancer patients had staging investigations (either CT and bone scans, bone scans only, or CT only). All images and reports on picture archiving and communication system were evaluated retrospectively. Results One hundred five of 156 patients had both CT TAP and bone scan within 10 days of each other. Of the total of 105 patients, 33 (31.4%) had concordant normal results on CT TAP and bone scan. There were 18/105 (17.1%) patients with extraosseous metastasis on CT with negative or inconclusive bone scan. Bone scans diagnosed peripheral osseous metastasis in 5/105 (4.7%), which were either skull or extremity metastasis outside CT TAP field of view. All of these 5 patients had other metastatic lesions within axial skeleton or soft tissues on CT and led to no change in patient management. Conclusions Our findings suggest routine use of bone scan in asymptomatic patients with locally advanced breast cancer did not change patient management.



  7. Magnetic Resonance Imaging of Intracranial Hypotension: Diagnostic Value of Combined Qualitative Signs and Quantitative Metrics
    imageObjective The aim of this study was to investigate whether the use of combination quantitative metrics (mamillopontine distance [MPD], pontomesencephalic angle, and mesencephalon anterior-posterior/medial-lateral diameter ratios) with qualitative signs (dural enhancement, subdural collections/hematoma, venous engorgement, pituitary gland enlargements, and tonsillar herniations) provides a more accurate diagnosis of intracranial hypotension (IH). Methods The quantitative metrics and qualitative signs of 34 patients and 34 control subjects were assessed by 2 independent observers. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of quantitative metrics and qualitative signs, and for the diagnosis of IH, optimum cutoff values of quantitative metrics were found with ROC analysis. Combined ROC curve was measured for the quantitative metrics, and qualitative signs combinations in determining diagnostic accuracy and sensitivity, specificity, and positive and negative predictive values were found, and the best model combination was formed. Results Whereas MPD and pontomesencephalic angle were significantly lower in patients with IH when compared with the control group (P < 0.001), mesencephalon anterior-posterior/medial-lateral diameter ratio was significantly higher (P < 0.001). For qualitative signs, the highest individual distinctive power was dural enhancement with area under the ROC curve (AUC) of 0.838. For quantitative metrics, the highest individual distinctive power was MPD with AUC of 0.947. The best accuracy in the diagnosis of IH was obtained by combination of dural enhancement, venous engorgement, and MPD with an AUC of 1.00. Conclusions This study showed that the combined use of dural enhancement, venous engorgement, and MPD had diagnostic accuracy of 100 % for the diagnosis of IH. Therefore, a more accurate IH diagnosis can be provided with combination of quantitative metrics with qualitative signs.



  8. Should Dual-Energy Computed Tomography Pulmonary Angiography Replace Single-Energy Computed Tomography Pulmonary Angiography in Pregnant and Postpartum Patients?
    imageObjective The study aims to compare single-energy (SE) and dual-energy (DE) computed tomography pulmonary angiography (CTPA) for evaluation of suspected pulmonary embolism in pregnant and postpartum patients. Materials and Methods Our study included 59 CTPA performed in pregnant/postpartum women (study group) comprised of 38 SE-CTPA and 21 DE-CTPA. The control group of 21 age- and weight-matched nonpregnant/nonpostpartum women underwent DE-CTPA. Two radiologists assessed pulmonary arterial enhancement, image quality, and artifacts. κ Test and analysis of variance were performed. Results Fourteen of 38 pregnant/postpartum women (37%) had suboptimal SE-CTPA compared with just 10% (2/21) suboptimal DE-CTPA studies (P = 0.02). Mean Hounsfield unit (HU) in the pulmonary trunk was 550 ± 68 HU in the DE-CTPA pregnant/postpartum group and 245 ± 12 HU in the SE-CTPA (P < 0.001). The mean volume computed tomography dose index in the pregnant/postpartum patients for DE-CTPA and SE-CTPA were 9 ± 2 and 19 ± 8 mGy, respectively (P < 0.001). Conclusions Dual-energy CTPA substantially increased arterial enhancement for evaluation of pulmonary embolism in pregnant and postpartum women compared with SE-CTPA.



  9. Development of Correction for Signal-to-Noise Ratio Using a T2* With Improved Phase Method
    imageObjective This study aims to improve the signal-to-noise ratio (SNR) of the phase image focusing T2* and to develop an improved phase (iPhase) image acquired high SNR. Methods The iPhase images of phantom and brain were acquired with multi-echo spoiled gradient-echo. The phantom component was a gadopentetate dimeglumine (Gd-DTPA) solution made of different concentrations (0.1, 0.5, and 1 wt%) and Gd-DTPA (0.1, 0.5, and 1 wt%) with agar (1.0 wt%). We applied the iPhase image to susceptibility weighed image (SWI) and evaluated SNR of SWI. Results In phantom study, SNRs of conventional SWI at each sample were 19.8, 15.7, 7.4, 20.0, 17.4, and 27.3, respectively. Signal-to-noise ratios of SWI derived from iPhase method were 29.5, 33.7, 21.7, 28.5, 24.3, and 14.7, respectively. Then, the SNR showed an improvement of 196% at maximum (for the Gd-DTPA 1 wt% sample). In healthy volunteer study, SWI derived from iPhase method had the good contrast between white matter and gray matter. Conclusions The iPhase image was able to improve the phase SNR. Moreover, iPhase method makes it possible to obtain a high SNR image when applying to SWI.



  10. Pulmonary Apical Opacities on Thin-Section Computed Tomography: Relationship to Primary Spontaneous Pneumothorax in Young Male Patients and Corresponding Histopathologic Findings
    imageObjective The purpose of this study was to test the hypothesis that apical opacities on computed tomography (CT) are related to occurrence of primary spontaneous pneumothorax (PSP) in young male patients. Methods We compared the frequency of apical opacities on thin-section CT between 70 male patients with PSP (PSP group) and 74 male patients without a history of PSP (non-PSP group). We also evaluated histopathologic findings of 39 specimens from 37 surgical cases in the PSP group. Results Apical opacities were significantly more frequent in the PSP group than in the non-PSP group (right side, P = 0.01; left side, P = 0.005). Histopathologically, subpleural band-like alveolar collapse was seen in 35 specimens (89.7%), which was always accompanied by fibroelastosis and fibroblastic foci. Conclusions Apical opacities on CT were significantly associated with PSP in young male patients. These apical opacities histopathologically correspond to fibrotic pleural thickening with subpleural alveolar collapse.


  11. Pretreatment 18F-Fluorodeoxyglucose Positron Emission Tomography Standardized Uptake Values and Tumor Size in Medically Inoperable Nonsmall Cell Lung Cancer Is Prognostic of Overall 2-Year Survival After Stereotactic Body Radiation Therapy
    imageObjective The aim of this study was to determine prognostic value of tumor size and metabolic activity on survival for patients with early stage nonsmall cell lung cancer receiving stereotactic body radiation therapy. Methods We retrospectively evaluated the patients who underwent positron emission tomography–computed tomography scan before stereotactic body radiation therapy treatment. Tumor diameter, tumor volume, maximum standardized uptake value (SUVmax), standardized uptake value (SUV) average, and SUV volume were obtained. Cox regression analyses were performed to determine the associations between tumor characteristics and survival. Results The patients with large tumors and high SUVmax have worse survival than patients with small tumors and low SUVmax (hazard ratio [HR] = 3.47, P = 0.007). Patients with small tumors and high SUVmax (HR = 1.80; P = 0.24) and large tumors and low SUVmax (HR = 1.55; P = 0.43) had increased risk of death compared with patients with small tumors and low SUVmax. Conclusions Both increased tumor size and metabolic activity are associated with increased risk of death. Combining size and metabolic activity together is superior for predicting 2-year survival and identifying patients for whom survival is statistically worse.



  12. Preliminary Results: Can Dual-Energy Computed Tomography Help Distinguish Cardiogenic Pulmonary Edema and Acute Interstitial Lung Disease?
    imageObjective We compared iodine concentration in pulmonary ground-glass opacity on iodine density images of contrast-enhanced chest dual-energy computed tomography (DECT) between patients with cardiogenic pulmonary edema (CPE) and acute interstitial lung disease (AILD). Methods Five of 12 patients who underwent contrast-enhanced chest DECT to exclude pulmonary embolism were clinically diagnosed with CPE and 7, with AILD. We compared the mean CT value on monochromatic images at 65 keV and iodine concentration on iodine density images between the affected and normal areas. Results The mean iodine concentrations were comparable between the affected and normal areas (P = 0.3048) in patients with CPE and were significantly higher in the affected than in the normal areas in those with AILD (P < 0.0001). Conclusions Measurement of iodine concentration in pulmonary ground-glass opacity of contrast-enhanced chest DECT has the potential to help distinguish CPE and AILD.



  13. The Value of Quality-Assured Magnetic Resonance Imaging of the Breast for the Early Detection of Breast Cancer in Asymptomatic Women
    imagePurpose The aim of this study was to evaluate the exclusive performance of quality-assured high-resolution breast magnetic resonance imaging (MRI) for early detection of breast cancer in a population of asymptomatic women. Materials and Methods A total of 1189 MRI examinations performed in 789 asymptomatic women (mean age, 51.1 years) were evaluated. All examinations were performed using open bilateral surface coil, dedicated compression device, and high spatial resolution (matrix, 512 × 512). Digital mammography was available for all participants. Assessment included density types, artifact level, and Breast Imaging Reporting and Data System classification. Evaluation was performed by 2 readers. In addition, a computer-assisted diagnosis (CAD) system was used for image assessment. Results Breast MRI showed density types I and II in 87.6% and artifacts categories III and IV in 3.1%. Study included 32 carcinomas (8 ductal carcinoma in situ, 24 invasive tumors). Both readers detected 29 of 32 correctly (sensitivity 90.6%). The variation between the readers was low (reader 1: specificity, 94.4% and positive predictive value (PPV), 25.7%; reader 2: specificity, 97.6% and PPV, 34.1%). Sensitivity of CAD was 62.5% (specificity, 84.4%; PPV, 5.2%). Digital mammography detected 13 of 32 carcinomas (sensitivity, 56.3%; specificity, 98.4%; PPV, 32.1%). Conclusions The exclusive use of quality-assured breast MRI allows the early detection of breast cancer with a high sensitivity and specificity. The CAD analysis of MRI does not give additional information but shows results comparable with digital mammography.



  14. Image Quality and Radiation Exposure Comparison of a Double High-Pitch Acquisition for Coronary Computed Tomography Angiography Versus Standard Retrospective Spiral Acquisition in Patients With Atrial Fibrillation
    imageObjective The aim of this study was to compare image quality and radiation dose of coronary computed tomography (CT) angiography performed with dual-source CT scanner using 2 different protocols in patients with atrial fibrillation. Methods Forty-seven patients with AF underwent 2 different acquisition protocols: double high-pitch (DHP) spiral acquisition and retrospective spiral acquisition. The image quality was ranked according to a qualitative score by 2 experts: 1, no evident motion; 2, minimal motion not influencing coronary artery luminal evaluation; and 3, motion with impaired luminal evaluation. A third expert solved any disagreement. Results A total of 732 segments were evaluated. The DHP group (24 patients, 374 segments) showed more segments classified as score 1 than the retrospective spiral acquisition group (71.3% vs 37.4%). Image quality evaluation agreement was high between observers (κ = 0.8). There was significantly lower radiation exposure for the DHP group (3.65 [1.29] vs 23.57 [10.32] mSv). Conclusions In this original direct comparison, a DHP spiral protocol for coronary CT angiography acquisition in patients with atrial fibrillation resulted in lower radiation exposure and superior image quality compared with conventional spiral retrospective acquisition.



  15. Physiological Laterality of Superficial Cerebral Veins on Susceptibility-Weighted Imaging
    imageObjective The purpose of this study is to evaluate whether laterality of the superficial cerebral veins can be seen on susceptibility-weighted imaging (SWI) in patients with no intracranial lesions that affect venous visualization. Methods We retrospectively evaluated 386 patients who underwent brain magnetic resonance imaging including SWI in our institute. Patients with a lesion with the potential to affect venous visualization on SWI were excluded. Two neuroradiologists visually evaluated the findings and scored the visualization of the superficial cerebral veins. Results Of the 386 patients, 315 (81.6%) showed no obvious laterality on venous visualization, 64 (16.6%) showed left-side dominant laterality, and 7 (1.8%) showed right-side dominant laterality. Conclusions Left-side dominant physiological laterality exists in the visualization of the superficial cerebral veins on SWI. Therefore, when recognizing left-side dominant laterality of the superficial cerebral veins on SWI, the radiologist must also consider the possibility of physiological laterality.


  16. Impact of SSF on Diagnostic Performance of Coronary Computed Tomography Angiography Within 1 Heart Beat in Patients With High Heart Rate Using a 256-Row Detector Computed Tomography
    imageObjective The aim of this study was to investigate the impact of a motion-correction algorithm on diagnostic accuracy of coronary computed tomography angiography (CCTA) within 1 heart beat in patients with high heart rate (HR) using a 256-row detector CT. Method Sixty-four consecutive patients with known or suspected coronary artery disease (symptomatic) and with HR of 75 beats per minute or greater (mean [SD] HR, 82.6 [7.3] beats per minute) undergoing CCTA and invasive coronary angiography within 4 weeks were prospectively enrolled. Coronary computed tomography angiography was performed with a 256-row detector CT (Revolution CT, GE Healthcare) using prospectively electrocardiography-triggered volume scan in 1 heart beat. All images were reconstructed using standard (STD) algorithm and a motion-correction algorithm reconstruction (Snapshot Freeze SSF; GE Healthcare) technique. The image quality of coronary artery segments was evaluated by 2 experienced radiologists using a 4-point scale based on the 18-segment model. Diagnostic accuracy was compared between STD and SSF for significant lumen stenosis (≥50%) of each segment with invasive coronary angiography as the reference standard for determining significant stenosis. Results The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value with STD and SSF were 93.7%, 85.1%, 50.2%, and 98.8% versus 91.9%, 95.8%, 77.9%, and 98.7% on per-segment assessment; 98.7%, 74.0%, 62.9%, and 99.2% versus 96.2%, 94.4%, 77.9%, and 98.7% on per-artery assessment; and 100%, 14.3%, 70.5%, and 100% versus 100%, 85.7%, 93.5%, and 100% on per-patient assessment, respectively. There was a significant difference in accuracy between STD and SFF on per-patient level 71.9% versus 95.3%, on per-artery level 81.6% versus 94.9%, and per-segment level 86.3% versus 95.3%, respectively. The area under receiver operating characteristics curve analysis also showed a significant improvement on diagnostic performance with the SSF technique versus with the STD algorithm on per-patient level (P < 0.001), with corresponding area under the curve being 0.91 (95% confidence interval, 0.79–1.00) and 0.60 (95% confidence interval, 0.44–0.75). The mean effective dose was 2.0 mSv. Conclusions Coronary computed tomography angiography can be performed in patients with high HR within 1 heart beat yielding low radiation dose. The use of SSF technique reconstruction for 1 heart beat CCTA achieves significant improvements in image quality and diagnostic value.



  17. The Effect of Single-Scan and Scan-Pair Intensity Inhomogeneity Correction Methods on Repeatability of Voxel-Based Morphometry With Multiple Magnetic Resonance Scanners
    imageObjective The aim of this study was to investigate the effects of single-scan and scan-pair intensity inhomogeneity correction methods on the repeatability of voxel-based morphometry (VBM) using images acquired with multiple magnetic resonance (MR) scanners. Methods Three-dimensional T1-weighed MR images of the brain were obtained from 22 healthy participants using each of 5 MR scanners, yielding 110 images (5 scanners × 22 subjects) in total. Six patterns of intensity inhomogeneity corrections (no correction, single-scan corrections, and scan-pair correction, and their combinations) were applied in the VBM procedure to investigate the effect of the corrections on the repeatability of gray and white matter volume measurements. Results Single-scan and scan-pair intensity inhomogeneity corrections significantly reduced the variance in spatially normalized gray and white matter volumes. However, combining the 2 methods did not significantly improve the repeatability when evaluated as whole brain. Conclusions Single-scan and scan-pair intensity inhomogeneity corrections improved the repeatability of gray and white matter volumes obtained by multiple MR scanners and assessed by VBM.



  18. The Influence of Contrast Agent's Osmolarity on Iodine Delivery Protocol in Coronary Computed Tomography Angiography: Comparison Between Iso-Osmolar Iodixanol-320 and Low-Osmolar Iomeprol-370
    imageObjectives This study aims to assess whether iodine-contained contrast agents with different osmolarity affect iodine delivery protocol during coronary computed tomography angiography (CCTA). Methods Patients who underwent CCTA were randomized to receive contrast media either iodixanol-320 (iso-osmolar group) or iopromide-370 (low-osmolar group). Contrast protocols were recorded. Tube voltage of 100 kV was chosen for patients with body mass index of less than or equal to 25 (n = 224) and tube voltage of 120 kV for patients with body mass index of greater than 25 (n = 165). Both groups applied automatic current modulation technique. Mean contrast enhancement of the ascending aorta, left main coronary artery, and descending aorta was calculated. Simulated contrast flow rate and iodine delivery rate (IDR) to reach a mean contrast enhancement level of 350 HU were calculated. Results A total of the 389 patients were enrolled in the study. To achieve the same contrast enhancement of 350 HU, iso-osmolar group required higher simulated contrast flow rate (3.90 vs 3.62 mL/s, P = 0.017) but lower simulated IDR (1.34 vs 1.25 g/s, P = 0.024) compared with low-osmolar group. Conclusions To maintain a similar level of contrast enhancement during CCTA, iodixanol-320 needs larger contrast flow rate with lower IDR compared with low-osmolar iopromide-370.



  19. Experience With Iterative Reconstruction Techniques for Abdominopelvic Computed Tomography in Morbidly and Super Obese Patients
    imageObjective The aim of this study was to investigate the diagnostic performance of abdominopelvic computed tomography (CT) images reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) algorithms in morbidly and super obese patients. Materials and Methods One hundred eighty-seven abdominopelvic CT examinations in portal venous phase were performed between February 2015 and February 2016 in 182 patients (mean age = 52 years, mean body mass index = 45.5). One hundred fourteen of 187 examinations were reconstructed using IR and 73 examinations were processed using FBP. Patients were further stratified based on body mass index. Sixty CT scans were reviewed by a single reader for image quality, image noise, and artifacts. Objective noise and attenuation were also determined. Size-specific dose estimate and CT dose index volume were compared and statistically analyzed. Results A diagnostic interpretation was rendered for all 187 examinations. A single-reader review of 60 cases showed greater diagnostic acceptability for IR when compared with FBP (image quality = 4.2 and 3.8 [P = 0.035], noise = 1.5 and 1.6 [P = 0.692], artifact = 1.4 and 1.5 [P = 0.759], respectively). For all examinations, the IR group had lower objective image noise (IR = 9.3 and FBP = 14.3; P < 0.001) and higher contrast-to-noise ratio (IR = 17.2 and FBP = 11.7; P < 0.001) without increase in radiation dose (size-specific dose estimate [IR = 15.1, FBP = 16.5 mGy; P = 0.045] and CT dose index volume [IR = 17.6, FBP = 18 mGy; P = 0.62]). Conclusions In morbidly and super obese patients, diagnostic quality images could be reliably generated with minimal artifacts and noise using newer generation scanners integrated with IR without increasing radiation dose.



  20. Repeatability of Non–Contrast-Enhanced Lower-Extremity Angiography Using the Flow-Spoiled Fresh Blood Imaging
    imagePurpose The aim of this study was to prospectively evaluate the repeatability of non–contrast-enhanced lower-extremity magnetic resonance angiography using the flow-spoiled fresh blood imaging (FS-FBI). Methods Forty-three healthy volunteers and 15 patients with lower-extremity arterial stenosis were recruited in this study and were examined by FS-FBI. Digital subtraction angiography was performed within a week after the FS-FBI in the patient group. Repeatability was assessed by the following parameters: grading of image quality, diameter and area of major arteries, and grading of stenosis of lower-extremity arteries. Two experienced radiologists blinded for patient data independently evaluated the FS-FBI and digital subtraction angiography images. Intraclass correlation coefficients (ICCs), sensitivity, and specificity were used for statistical analysis. Results The grading of image quality of most data was satisfactory. The ICCs for the first and second measures were 0.792 and 0.884 in the femoral segment and 0.803 and 0.796 in the tibiofibular segment for healthy volunteer group, 0.873 and 1.000 in the femoral segment, and 0.737 and 0.737 in the tibiofibular segment for the patient group. Intraobserver and interobserver agreements on diameter and area of arteries were excellent, with ICCs mostly greater than 0.75 in the volunteer group. For stenosis grading analysis, intraobserver ICCs range from 0.784 to 0.862 and from 0.778 to 0.854, respectively. Flow-spoiled fresh blood imaging yielded a mean sensitivity and specificity to detect arterial stenosis or occlusion of 90% and 80% for femoral segment and 86.7% and 93.3% for tibiofibular segment at least. Conclusions Lower-extremity angiography with FS-FBI is a reliable and reproducible screening tool for lower-extremity atherosclerotic disease, especially for patients with impaired renal function.


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