Epicardial fat volume measured on nongated chest CT is a predictor of coronary artery disease.

OBJECTIVE: To investigate whether epicardial fat volume (EFV) quantified on ECG-nongated noncontrast CT (nongated-NCCT) could be used as a reliable and reproducible predictor for coronary artery disease (CAD). METHODS: One hundred seventeen subjects (65 men, mean age 66.6 ± 11.9 years) underwent coronary CT angiography (CCTA) and nongated-NCCT during a single session because of symptoms suggestive of CAD. Two observers independently quantified EFV on both images. Correlation between CCTA-EFV and nongated-NCCT-EFV was assessed using Pearson's correlation coefficient and Bland-Altman plots. Inter-observer agreement was analyzed using concordance correlation coefficients (CCC). Coronary risk factors including EFV were compared between CAD-positive (> 50% stenosis) and CAD-negative groups. The association between EFV and CAD was analyzed using multivariate logistic regression. ROC analysis was performed, and AUC was compared with DeLong's method. RESULTS: Seventy-four subjects were diagnosed with CAD. An excellent correlation was noted between CCTA-EFV and nongated-NCCT-EFV (r = 0.948, p < 0.001), despite the systematic difference between both measurements (mean bias, 1.26). Inter-observer agreement was nearly perfect (CCC, 0.988 and 0.985 for CCTA and nongated-NCCT, respectively, p < 0.001). Significant differences were noted between subjects with versus without CAD in age, hypertension, and EFV on both types of images (p ≤ 0.026). Multivariate analysis revealed that increased EFV on CCTA (odds ratio 1.185, p = 0.003) and nongated-NCCT (odds ratio 1.20, p = 0.015) was independently associated with CAD. There was no significant difference between CCTA-EFV and nongated-NCCT-EFV in AUC for the prediction of CAD (0.659 vs 0.665, p = 0.706). CONCLUSIONS: Despite the absence of ECG gating, EFV measured on NCCT may serve as a reproducible predictor for CAD with accuracy equivalent to EFV measured on CCTA. KEY POINTS: • Despite the absence of ECG gating, the EFV on NCCT provides nearly perfect inter-observer reproducibility and shows excellent correlation with measurements on gated CCTA. • EFV on nongated-NCCT may serve as an independent biomarker for predicting coronary artery disease with accuracy equivalent to that of EFV on gated CCTA.

Correction to: Epicardial fat volume measured on nongated chest CT is a predictor of coronary artery disease.

The original version of this article, published on 11 March 2019, unfortunately contained a mistake. The following correction has therefore been made in the original: the presentation of Fig. 5 was incorrect. The corrected figure is given below.

Usefulness of the Short-Echo Time Cube Sequence at 3-T Magnetic Resonance Cholangiopancreatography: Prospective Comparison With the Conventional 3-Dimensional Fast Spin-Echo Sequence.

OBJECTIVES: We evaluated prospectively the clinical use of the short-echo time (TE) Cube sequence for magnetic resonance cholangiopancreatography (MRCP) at 3 T. METHODS: Using a 3-T unit, we subjected 41 consecutive patients to short-TE Cube MRCP and conventional 3-dimensional fast spin-echo (3D-FSE) MRCP. Two radiologists independently rated the image quality and the visibility of the right and left hepatic, cystic, common bile, and main pancreatic ducts and the gallbladder on a 4-point scale. The averaged visual scores by 2 readers for the image quality were calculated, and the artifacts were evaluated in cases with relatively lower (<3) score. The signal-to-noise ratio, contrast-to-noise ratio, and acquisition time were evaluated by quantitative analysis. RESULTS: The visual scores of the common bile duct (P < 0.05), cystic duct (P < 0.01), and gallbladder (P < 0.01) were significantly higher for Cube than 3D-FSE MRCP. Signal-to-noise ratio was also significantly higher for Cube than 3D-FSE MRCP (P < 0.01). There was no significant difference in the image acquisition time (352.1 ± 93.0 vs 314.1 ± 126.2 seconds, P = 0.059). Four cases on 3D-FSE MRCP and 2 cases on Cube MRCP have relatively lower image quality; however, the difference was not significant (P = 0.18). CONCLUSIONS: The visibility of biliary structures is significantly better on short-TE Cube MRCP than conventional 3D-FSE MRCP images at a clinically acceptable acquisition time.

Clinical impact of 3-dimensional balanced turbo-field-echo magnetic resonance cholangiopancreatography at 3 T: prospective intraindividual comparison with 3-dimensional turbo-spin-echo magnetic resonance cholangiopancreatography.

OBJECTIVE: The objective of this study was to evaluate the clinical utility of 3-dimensional (3D) balanced turbo-field-echo (BTFE) magnetic resonance cholangiopancreatography (MRCP) with gate and track acquisition at 3 T. METHODS: Using a 3-T unit, we subjected 52 consecutive patients to 3D BTFE MRCP with the navigator-gated technique and 3D turbo-spin-echo volume isotropic T2-weighted acquisition (VISTA) MRCP with the navigator-triggered technique. Two radiologists independently rated the image quality and visibility of the right and left hepatic duct, cystic duct, common bile duct, gallbladder, and main pancreatic duct using a 4-point scale. The signal-to-noise ratio, contrast-to-noise ratio, and the acquisition time were evaluated by quantitative analysis. RESULTS: The visual scores of the cystic duct, common bile duct, gallbladder, and overall image quality were significantly higher for BTFE than VISTA MRCP (P < 0.01). The score for the main pancreatic duct was significantly higher with VISTA MRCP (P < 0.01). The image acquisition time was significantly shorter with BTFE than VISTA MRCP (139.8 ± 45.4 vs 416.9 ± 108.3 seconds, P < 0.01). There was no significant difference in signal-to-noise ratio and contrast-to-noise ratio. CONCLUSIONS: Three-dimensional BTFE MRCP yields significantly better image quality and visibility of large biliary structures than VISTA MRCP at a significantly shorter acquisition time. Volume isotropic T2-weighted acquisition MRCP provides detailed information on the main pancreatic duct that tends to be obscure on the 3D BTFE sequence.

Characterization of Liver Tumors by Diffusion-Weighted Imaging: Comparison of Diagnostic Performance Using the Mean and Minimum Apparent Diffusion Coefficient.

PURPOSE: To determine the minimum apparent diffusion coefficient (ADC(min)) values of benign and malignant hepatic lesions based on diffusion-weighted imaging and to compare the diagnostic performance of ADC(min) and mean ADC (ADC(mean)) values for differentiating between benign and malignant tumors of the liver. MATERIALS AND METHODS: We retrospectively subjected 240 patients with 195 malignant (hepatocellular carcinoma [HCC], n = 137; metastases, n = 44; cholangiocellular carcinoma [CCC], n = 14) and 45 benign tumors (hemangiomas, n = 37; focal nodular hyperplasia [FNH], n = 8). Both ADC(mean) and ADC(min) were evaluated independently by 2 readers, the sensitivity and specificity for the detection of malignancy were calculated, and receiver operating characteristic (ROC) curves were generated. To determine interobserver agreement, we calculated the Pearson correlation coefficient. RESULTS: Mean ADC (×10 mm/s) was 1.19 for malignant (HCC, 1.15; metastasis, 1.23; CCC, 1.51) and 2.01 for benign tumors (hemangioma, 2.09; FNH, 1.52; P < 0.001). Minimum ADC was 0.81 for malignant (HCC, 0.79; metastasis, 0.81; CCC, 0.91) and 1.62 for benign tumors (hemangioma, 1.66; FNH, 1.28; P < 0.001). The sensitivity, specificity, and the calculated area under the ROC curve for diagnosing malignant lesions were 86.2%, 86.7%, and 0.942 (reader 1) and 88.7%, 88.9%, and 0.939 (reader 2) for ADC(mean); they were of 92.3%, 97.8%, and 0.984 (reader 1) and 94.9%, 97.8%, and 0.983 (reader 2) for ADC(min). CONCLUSIONS: Mean ADC and ADC(min) were valuable for differentiating between malignant and benign hepatic lesions. The area under the ROC curve of ADC(min) was significant higher than that of ADC(mean).

Extracapsular extension of prostate cancer: diagnostic value of combined multiparametric magnetic resonance imaging and isovoxel 3-dimensional T2-weighted imaging at 1.5 T.

OBJECTIVE: The objective of this study was to assess whether adding isovoxel 3-dimensional T2-weighted imaging (volume isotropic T2-weighted acquisition [VISTA]) to multiparametric magnetic resonance imaging (mp-MRI) improves the ability to diagnose the extracapsular extension (ECE) of prostate cancer. METHODS: Two radiologists independently evaluated ECE on images acquired with mp-MRI only (method A) and mp-MRI plus VISTA (method B) in 50 men who had undergone prostatectomy. We also compared the signal-to-noise ratio of the tumor on T2WI and VISTA scans. RESULTS: Sensitivity, specificity, and accuracy were higher with method B. For both readers, specificity, accuracy, and the area under the receiver operating characteristic curve of method B were significantly higher than those of method A (reader 1: P = 0.028, 0.025, and 0.006; reader 2: P = 0.017, 0.0071, and 0.018). The signal-to-noise ratio was significantly higher on T2-weighted imaging than VISTA images (9.21 [SD, 2.46] vs 7.30 [SD, 1.87], P < 0.01). CONCLUSIONS: The addition of VISTA to mp-MRI improves the diagnostic value for ECE significantly.

Triage of low-risk prostate cancer patients with PSA levels 10 ng/ml or less: comparison of apparent diffusion coefficient value and transrectal ultrasound-guided target biopsy.

OBJECTIVE: The purpose of our study was to identify low-risk prostate cancer on the basis of the D'Amico clinical risk score in patients with prostate-specific antigen (PSA) levels 10 ng/mL or less who had undergone radical prostatectomy by comparing apparent diffusion coefficient (ADC) with transrectal ultrasound (TRUS)-guided target biopsy. MATERIALS AND METHODS: In the preliminary study, we used receiver operating characteristic (ROC) analysis and determined the cutoff ADC to identify prostate cancer with a Gleason score of 6 or less for 117 patients. In the primary study, we assessed the combination of routine MRI (T2-weighted and diffusion-weighted imaging) plus the cutoff ADC value ("method A") to identify low-risk prostate cancer for another 89 patients. Their diagnostic value was compared with that of routine MRI combined with the Gleason score obtained from TRUS-guided target biopsies ("method B"). RESULTS: The preliminary study showed that a mean ADC of 1.04 × 10(-3) mm(2)/s was the best cutoff. In the primary study, accuracy was statistically higher with method A for each reader (p = 0.041). CONCLUSION: In patients with PSA levels 10 ng/mL or less, the combination of MRI findings plus the cutoff ADC is significantly more accurate for the identification of low-risk prostate cancer than is the combination of MRI followed by TRUS-guided target biopsy.

Preoperative evaluation of the cystic duct for laparoscopic cholecystectomy: comparison of navigator-gated prospective acquisition correction- and conventional respiratory-triggered techniques at free-breathing 3D MR cholangiopancreatography.

OBJECTIVE: To evaluate the quality of magnetic resonance cholangiopancreatography (MRCP) images obtained with a three-dimensional navigator-gated (NG) technique and compare findings with conventional respiratory-triggered (RT) images in pre-laparoscopic cholecystectomy patients. METHODS: Turbo-spin-echo (TSE) RT-MRCP (average 242 s) and balanced turbo-field-echo (bTFE) NG-MRCP (average 263 s) were acquired at 1.5-T MRI for 49 pre-laparoscopic cholecystectomy patients. Two radiologists independently assessed image quality, visibility of anatomical structures, common bile duct (CBD) stones, and signal-to-noise ratios (SNRs). Interobserver agreement was also evaluated. RESULTS: The anatomical details of the cystic duct were clearly demonstrated in 33 (67.3 %, reader A) and 35 (71.4 %, reader B) patients on RT-MRCP, and in 45 (91.8 %) and 44 (89.7 %) patients on NG-MRCP. On NG-MRCP, visualisation of the cystic duct (3.22/3.12), its origin (3.57/3.55), and the gallbladder(3.61/3.59) was statistically better than on RT-MRCP (2.90/2.78, 3.29/3.12, 2.98/2.88, respectively). The overall image quality was statistically better on NG-MRCP than RT-MRCP. Each technique identified the presence of CBD stones in all affected patients. The SNR was significantly higher on NG-MRCP (CHD 22.40, gallbladder 17.13) than RT-MRCP (CHD 17.05, gallbladder 9.30). Interobserver agreement was fair to perfect. CONCLUSION: Navigator-gated MRCP is more useful than respiratory-triggered MRCP for evaluating the gallbladder and cystic duct in patients scheduled for laparoscopic cholecystectomy. KEY POINTS: • Magnetic resonance cholangiopancreatography (MRCP) provides important cystic duct information before laparoscopic cholecystectomy. • Navigator-gated (NG) MRCP images were better than conventional respiratory-triggered (RT) MRCP. • The signal-to-noise ratio was significantly higher for NG-MRCP than for conventional RT-MRCP. • Balanced turbo-field-echo NG-MRCP is useful for evaluating the gallbladder and cystic duct.

Evaluation of deep vein thrombosis with reduced radiation and contrast material dose at computed tomography venography: clinical application of a combined iterative reconstruction and low-tube-voltage technique.

BACKGROUND: Computed tomography venography (CTV) is clinically useful and widely available for the detection of deep vein thrombosis. Disadvantages of CTV are the need for a larger amount of i.v. contrast material (CM) and radiation exposure. A low-tube-voltage technique with iterative reconstruction may overcome this problem. The aim of this study was to investigate the effects of hybrid iterative reconstruction (HIR) on image quality at low-tube-voltage CTV. METHODS AND RESULTS: Forty patients (26 women, 14 men; mean age, 59.2±18.3 years) underwent CTV under an 80- or 120-kV protocol (CT dose index volume=10.3 mGy vs. 14.9 mGy, CM dose=540 mgI/kg vs. 690 mgI/kg) on a 64-detector CT. Quantitative parameters (ie, venous attenuation, image noise, and contrast-to-noise ratio [CNR]) were calculated and the image quality was scored on a 4-point scale. In step 1, the 80- and 120-kV protocols were compared under filtered back projection (FBP). In step 2, the 80-kV protocol with HIR was compared with the 120-kV protocol with FBP. In step 1, the visual scores were significantly higher under the 120-kV protocol; there was no significant difference in CNR between the protocols. In step 2, CNR was significantly higher under the 80-kV protocol with HIR than the 120-kV protocol with FBP. The visual scores of the 2 protocols were comparable. CONCLUSIONS: The 80-kV CTV with HIR allows for a reduction in the radiation dose by 30% and the CM dose by 20% without image quality degradation.

Clinical application of navigator-gated three-dimensional balanced turbo-field-echo magnetic resonance cholangiopancreatography at 3 T: prospective intraindividual comparison with 1.5 T.

OBJECTIVE: To evaluate and compare the clinical utility of balanced turbo-field-echo (BTFE) magnetic resonance cholangiopancreatography (MRCP) sequences obtained at 3 and 1.5 T. METHODS: We acquired three-dimensional (3D) BTFE MRCP scans with a navigator-gated technique at 3 T on a different day after 1.5 T in 39 consecutive patients. Two radiologists independently rated the image quality and visibility of anatomical structures (right and left hepatic duct, cystic duct, gallbladder, common bile duct, and main pancreatic duct) using a four-point scale. For quantitative analysis, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and acquisition time were evaluated. RESULTS: All visual scores tended to be higher for 1.5 T than 3 T images. There was a significant difference in the image quality and the depiction of the main pancreatic duct (p < 0.01). The image acquisition time was significantly shorter for 3 T than 1.5 T (199.3 ± 40.1 vs. 264.0 ± 86.5 s, p < 0.01). There was no significant difference in SNR and CNR. CONCLUSIONS: 3D-BTFE MRCP scans acquired at 3 T were of sufficient image quality with respect to the biliary tree. SNR and CNR were comparable on 3 and 1.5 T scans, although the acquisition time was significantly shorter with the 3 T scanner.

Clinical utility of the normalized apparent diffusion coefficient for preoperative evaluation of the aggressiveness of prostate cancer.

PURPOSE: Normalization of the apparent diffusion coefficient (ADC) may overcome ADC variability attributable to different patient and/or technical factors. The purpose of this study was to compare the efficacy of ADC and the normalized ADC (nADC) for differentiating between prostate cancer with a Gleason score (GS) = 6 and GS > 6 and to identify an optimum reference for nADC calculations. MATERIALS AND METHODS: Our study population comprised 58 patients who underwent diffusion-weighted MRI followed by radical prostatectomy. The nADC of the prostate cancer was calculated as ADC (cancer)/ADC (reference) by using the obturator internus muscle, urine in the bladder, and a 20-ml saline bottle placed on the groin as references. We performed receiver operating characteristic (ROC) analysis to identify the optimum reference for nADC calculations. RESULTS: To differentiate between GS = 6 and GS > 6 prostate cancer, the area under the ROC curve of the nADC obtained with a saline bottle as reference was best (0.85) and significantly better than the area under the ADC ROC curve (0.71). CONCLUSIONS: nADC is superior to ADC for estimating the aggressiveness of prostate cancer. It is a noninvasive technique that aids in the selection of appropriate treatments.

Value of knowledge-based iterative model reconstruction in low-kV 256-slice coronary CT angiography.

BACKGROUND: Most current iterative reconstruction algorithms for CT imaging are a mixture of iterative reconstruction and filtered back projection. The value of "fully" iterative reconstruction in coronary CT angiography remains poorly understood. OBJECTIVE: We aimed to assess the value of the knowledge-based iterative model reconstruction (IMR) algorithm on the qualitative and quantitative image quality at 256-slice cardiac CT. METHODS: We enrolled 21 patients (mean age: 69 ± 11 years) who underwent retrospectively ECG gated coronary CT anhgiography at 100 kVp tube voltage. Images were reconstructed with the filtered back projection (FBP), hybrid iterative reconstruction (IR), and IMR algorithms. CT attenuation and the contrast-to-noise ratio (CNR) of the coronary arteries were calculated. With the use of a 4-point scale, 2 reviewers visually evaluated the coronary arteries and cardiac structures. RESULTS: The mean CT attenuation of the proximal coronary arteries was 369.3 ± 73.6 HU, 363.9 ± 75.3 HU, and 363.3 ± 74.5 HU, respectively, for FBP, hybrid IR, and IMR and was not significantly different. The image noise of the proximal coronary arteries was significantly lower with IMR (11.3 ± 2.8 HU) than FBP (51.9 ± 12.9 HU) and hybrid IR (23.2 ± 5.2 HU). The mean CNR of the proximal coronary arteries was 9.4 ± 2.4, 20.2 ± 4.7, and 41.8 ± 9.5 with FBP, hybrid IR and IMR, respectively; it was significantly higher with IMR. The best subjective image quality for coronary vessels was obtained with IMR (proximal vessels: FBP, 2.6 ± 0.5; hybrid IR, 3.4 ± 0.5; IMR, 3.8 ± 0.4; distal vessels: FBP, 2.3 ± 0.5; hybrid IR. 3.1 ± 0.5; IMR, 3.7 ± 0.5). IMR also yielded the best visualization for cardiac systems, that is myocardium and heart valves. CONCLUSION: The novel knowledge-based IMR algorithm yields significantly improved CNR and better subjective image quality of coronary vessels and cardiac systems with reliable CT number measurements for cardiac CT imaging.