Comparisons of Hepatobiliary Phase Imaging Using Combinations of Parallel Imaging and Variable Degrees of Compressed Sensing With Use of Parallel Imaging Alone.

OBJECTIVE: This study aimed to compare the image quality in the hepatobiliary phase images of gadoxetic acid-enhanced liver magnetic resonance imaging using parallel imaging (PI) and compressed sensing (CS) reconstruction, using variable CS factors with the standard method using the PI technique. METHODS: In this study, 64 patients who underwent gadoxetic acid-enhanced liver magnetic resonance imaging at 3.0 T were enrolled. Hepatobiliary phase images were acquired 6 times using liver acquisition with volume acceleration (LAVA) and CS reconstruction with 5 CS factors 1.4, 1.6, 1.8, 2.0, and 2.5 (LAVA-CS 1.4, 1.6, 1.8, 2.0, and 2.5) and standard LAVA (LAVA-noCS). For objective analysis, the signal intensity ratios (SIRs) of the liver-to-spleen (SIR liver/spleen ), liver-to-portal vein (SIR liver/portal vein ), and liver-to-fat (SIR liver/fat ) were estimated. For subjective analysis, 2 radiologists independently evaluated the quality of all the images. RESULTS: The objective analysis demonstrated no significant difference in all evaluation parameters of all the images. Subjective analysis revealed that the scores of all evaluation items were higher for LAVA-noCS images than for LAVA-CS images, and only LAVA-CS 1.4 did not significantly differ from LAVA-noCS in all evaluation items ( P = 1.00 in 2 readers). CONCLUSIONS: A CS factor of 1.4 in the hepatobiliary phase image with combined PI and CS can reduce the scan time without degrading the image quality compared with the standard method.

Triple-negative breast cancer on contrast-enhanced MRI and synthetic MRI: A comparison with non-triple-negative breast carcinoma.

PURPOSE: This study aimed to compare the characteristics of triple-negative breast cancer (TNBC) with non-TNBC on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and synthetic MRI. METHOD: This retrospective study included 79 patients with histopathologically proven breast cancer (TNBC: 16, non-TNBC: 63) who underwent synthetic MRI. Using synthetic MR images, we obtained T1 and T2 relaxation times in breast lesions before (Pre-T1, Pre-T2, Pre-PD) and after (Gd-T1, Gd-T2, Gd-PD) contrast agent injection. Subsequently, we calculated the ΔT1 (Pre-T1 - Gd-T1), ΔT2 (Pre-T2 - Gd-T2), Pre-T1/T2, and Gd-T1/T2. We compared the aforementioned quantitative values, as well as several morphologic features between TNBCs and non-TNBCs that were identified on DCE-MRI. RESULTS: The multivariate analyses revealed that the Pre-T2 (P = 0.037) and the presence of rim enhancement (P-RIM) (P = 0.034) were significant and independent predictors of TNBC. The area under the receiver operating characteristics curve for all breast cancers was greater when a combination of Pre-T2 and P-RIM (Pre-T2＋P-RIM; Method 3, AUC (area under the curve) = 0.858) was used to distinguish between TNBCs and non-TNBCs versus the use of either Pre-T2 alone (Method 1, AUC = 0.786) or P-RIM alone (Method 2, AUC = 0.747). CONCLUSIONS: Pre-T2 obtained using synthetic MRI and P-RIM identified on DCE-MRI allowed the differentiation between TNBCs and non-TNBCs. However, these results are preliminary and need to be verified by further studies.

Enhanced Masses on Contrast-Enhanced Breast: Differentiation Using a Combination of Dynamic Contrast-Enhanced MRI and Quantitative Evaluation with Synthetic MRI.

BACKGROUND: The addition of synthetic MRI might improve the diagnostic performance of dynamic contrast-enhanced MRI (DCE-MRI) in patients with breast cancer. PURPOSE: To evaluate the diagnostic value of a combination of DCE-MRI and quantitative evaluation using synthetic MRI for differentiation between benign and malignant breast masses. STUDY TYPE: Retrospective, observational. POPULATION: In all, 121 patients with 131 breast masses who underwent DCE-MRI with additional synthetic MRI were enrolled. FIELD STRENGTH/SEQUENCE: 3.0 Tesla, T1 -weighted DCE-MRI and synthetic MRI acquired by a multiple-dynamic, multiple-echo sequence. ASSESSMENT: All lesions were differentiated as benign or malignant using the following three diagnostic methods: DCE-MRI type based on the Breast Imaging-Reporting and Data System; synthetic MRI type using quantitative evaluation values calculated by synthetic MRI; and a combination of the DCE-MRI + Synthetic MRI types. The diagnostic performance of the three methods were compared. STATISTICAL TESTS: Univariate (Mann-Whitney U-test) and multivariate (binomial logistic regression) analyses were performed, followed by receiver-operating characteristic curve (AUC) analysis. RESULTS: Univariate and multivariate analyses showed that the mean T1 relaxation time in a breast mass obtained by synthetic MRI prior to injection of contrast agent (pre-T1 ) was the only significant quantitative value acquired by synthetic MRI that could independently differentiate between malignant and benign breast masses. The AUC for all enrolled breast masses assessed by DCE-MRI + Synthetic MRI type (0.83) was significantly greater than that for the DCE-MRI type (0.70, P < 0.05) or synthetic MRI type (0.73, P < 0.05). The AUC for category 4 masses assessed by the DCE-MRI + Synthetic MRI type was significantly greater than that for those assessed by the DCE-MRI type (0.74 vs. 0.50, P < 0.05). DATA CONCLUSION: A combination of synthetic MRI and DCE-MRI improves the accuracy of diagnosis of benign and malignant breast masses, especially category 4 masses. Level of Evidence 4 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:381-391.

Dual-energy computed tomography for evaluation of breast cancer: value of virtual monoenergetic images reconstructed with a noise-reduced monoenergetic reconstruction algorithm.

PURPOSE: To evaluate the image quality and lesion visibility of virtual monoenergetic images (VMIs) reconstructed using a new monoenergetic reconstruction algorithm (nMERA) for evaluation of breast cancer. MATERIALS AND METHODS: Forty-two patients with 46 breast cancers who underwent 4-phasic breast contrast-enhanced computed tomography (CT) using dual-energy CT (DECT) were enrolled. We selected the peak enhancement phase of the lesion in each patient. The selected phase images were generated by 120-kVp-equivalent linear blended (M120) and monoenergetic reconstructions from 40 to 80 keV using the standard reconstruction algorithm (sMERA: 40, 50, 60, 70, 80) and nMERA (40 +, 50 +, 60 +, 70 +, 80 +). The contrast-to-noise ratio (CNR) was calculated and objectively analyzed. Two independent readers subjectively scored tumor visibility and image quality each on a 5-point scale. RESULTS: The CNR at 40 + and tumor visibility scores at 40 + and 50 + were significantly higher than those on M120. The CNR at 50 + was not significantly different from that on M120. However, the overall image quality score at 40 + was significantly lower than that at 50 + and on M120 (40 + vs M120, P < 0.0001 and 40 + vs 50 +, P = 0.0001). CONCLUSIONS: VMI reconstructed with nMERA at 50 keV is preferable for evaluation of patients with breast cancer.

Dual-Energy Computed Tomography in Patients With Small Hepatocellular Carcinoma: Utility of Noise-Reduced Monoenergetic Images for the Evaluation of Washout and Image Quality in the Equilibrium Phase.

PURPOSE: This study aimed to evaluate the utility of virtual monoenergetic images for detecting washout of small (≤2 cm) hepatocellular carcinoma (HCC) in the equilibrium phase. METHODS: We performed 120-kVp-equivalent linear-blended (M120) and monoenergetic reconstructions from 40 to 90 keV by standard (40, 50, 60, 70, 80, 90) and novel noise-reduced (nMERA: 40+, 50+, 60+, 70+, 80+, 90+) monoenergetic reconstruction algorithms. Image quality and tumor visibility of delayed washout of HCCs in the equilibrium phase were compared between standard monoenergetic reconstruction algorithm and nMERA by objective and subjective analyses. RESULTS: Contrast-to-noise ratio of the tumor at 40+ was the highest, whereas the score of tumor visibility peaked at 50+. The score of overall image quality at 40+ was significantly lower than those on all other image series, and the image quality among other image series were not significantly different. CONCLUSIONS: Virtual monoenergetic image reconstructed with nMERA 50+ was most appropriate to detect washout of small HCCs.

Using a Motion Sensor-Equipped Smartphone to Facilitate CT-Guided Puncture.

PURPOSE: To demonstrate the use of "Smart Puncture," a smartphone application to assist conventional CT-guided puncture without CT fluoroscopy, and to describe the advantages of this application. MATERIALS AND METHODS: A puncture guideline is displayed by entering the angle into the application. Regardless of the angle at which the device is being held, the motion sensor ensures that the guideline is displayed at the appropriate angle with respect to gravity. The angle of the smartphone's liquid crystal display (LCD) is also detected, preventing needle deflection from the CT slice image. Physicians can perform the puncture procedure by advancing the needle using the guideline while the smartphone is placed adjacent to the patient. In an experimental puncture test using a sponge as a target, the target was punctured at 30°, 50°, and 70° when the device was tilted to 0°, 15°, 30°, and 45°, respectively. The punctured target was then imaged with a CT scan, and the puncture error was measured. RESULTS: The mean puncture error in the plane parallel to the LCD was less than 2°, irrespective of device tilt. The mean puncture error in the sagittal plane was less than 3° with no device tilt. However, the mean puncture error tended to increase when the tilt was increased. CONCLUSION: This application can transform a smartphone into a valuable tool that is capable of objectively and accurately assisting CT-guided puncture procedures.

Different enhancement of the hepatic parenchyma in dynamic CT for patients with normal liver and chronic liver diseases and with the dose of contrast medium based on body surface area.

PURPOSE: The purpose of this study was to characterize hepatic parenchymal enhancement for normal and diseased liver in dynamic computed tomography (CT) with the dose of contrast medium calculated on the basis of body surface area (BSA). MATERIALS AND METHODS: The records of 328 consecutive patients who underwent triple-phase contrast-enhanced CT were retrospectively reviewed. The patients were divided into four groups: normal liver (n = 125), chronic hepatitis (CH) (n = 92), Child-Pugh grade A liver cirrhosis (LC-A) (n = 78), and Child-Pugh grade B liver cirrhosis (LC-B) (n = 33). All patients received 22 g I m(-2) as contrast material, calculated on the basis of BSA. CT values were measured in the region of interest during the pre-contrast, arterial, and portal phases, and the change in the CT value (ΔHU, where HU is Hounsfield units) compared with pre-contrast images was calculated. RESULTS: Mean ΔHU for the hepatic parenchyma for the normal liver, CH, LC-A, and LC-B groups during the portal phase was 55.5 ± 11.8 HU, 55.2 ± 12.5 HU, 50.0 ± 13.0 HU, and 43.0 ± 12.7 HU, respectively; generalized estimating equation analysis showed the differences were significant (p < 0.01). CONCLUSION: Hepatic parenchymal enhancement during the portal phase decreased as the severity of chronic liver damage increased.

Incidence for progression of hypervascular HCC in hypovascular hepatic nodules showing hyperintensity on gadoxetic acid-enhanced hepatobiliary phase in patients with chronic liver diseases.

PURPOSE: The purpose of this study was to elucidate the incidence and risk factors for the progression of hyperintense nodules, observed in the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI), to hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Hypovascular nodules (n = 157) showing hyperintensity in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI were examined in 41 patients. All patients underwent computed tomography (CT) during hepatic arteriography and CT during arterial portography within one month of Gd-EOB-DTPA-enhanced MRI. The incidence of progression to hypervascular or classical HCC was calculated using the Kaplan-Meier method. RESULTS: Tumor size was determined by univariate and multivariate analysis to be an important risk factor of hypervascularization (p = 0.041, odds ratio 1.135). The cumulative incidences of hypervascularization in hypovascular nodules showing hyperintensity on the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI were 2.4, 4.5, and 6.2 % at 12, 24, and 36 months, respectively. The incidence of hypervascularization was significantly increased in nodules >10 mm in diameter (p = 0.00035). CONCLUSION: In patients with chronic liver disease, hypovascular nodules presenting as hyperintense in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI and >10 mm in diameter have malignant potential for progression to hypervascular HCC and require careful management.

Portal biliopathy diagnosed using color Doppler and contrast-enhanced ultrasound.

Portal biliopathy is a morphological abnormality of the biliary ductal and gallbladder wall associated with portal hypertension. A patient with essential thrombocythemia was initially diagnosed with extrahepatic portal vein obstruction (EHPVO). The contrast-enhanced computed tomography (CT) findings were similar to those of cholangiocarcinoma or sclerosing cholangitis. However, color Doppler and contrast-enhanced ultrasound (US) were more specific. The paracholedocheal veins around the bile ducts appeared as beads soon after the injection of contrast medium, followed by linear enhancement of the epicholedochal veins and the gradual enhancement of the whole bile ducts. These findings led to a diagnosis of portal biliopathy, which prevented the patient from having to endure hazardous procedures such as bile duct biopsies. Color Doppler and contrast-enhanced US findings are useful for diagnosing or ruling out portal biliopathy in patients who present with EHPVO.

Risk of hypervascularization in small hypovascular hepatic nodules showing hypointense in the hepatobiliary phase of gadoxetic acid-enhanced MRI in patients with chronic liver disease.

PURPOSE: The purpose of this study was to elucidate the incidence and risk factors for the progression of hypointense nodules observed in the hepatobiliary phase of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI) of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Hypovascular nodules (112) showing hypointensity in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI were examined in 54 patients. All patients underwent computed tomography during hepatic arteriography and computed tomography during arterial portography (CTAP) within a month after Gd-EOB-DTPA-enhanced MRI. According to the tumor size, 112 nodules were divided into two groups: those >10 mm in diameter (group A, n = 39) and those ≤10 mm in diameter (group B, n = 73). The incidence of progression to hypervascular HCC was calculated using the Kaplan-Meier method. RESULTS: The incidence of hypervascularization was significantly higher in group A nodules than in group B nodules (p < 0.0001). Tumor size (p < 0.0001) and hypoattenuation in CTAP (p = 0.0004) showed significant correlation with hypervascularization. CONCLUSION: Hypointense nodules observed in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI with diameters of >10 mm had a high probability of hypervascularization.

Widespread metastases from sarcomatoid renal cell carcinoma detected by (18)F-FDG positron emission tomography/computed tomography.

We present a case of sarcomatoid renal cell carcinoma (RCC). Although preoperative computed tomography (CT) scans demonstrated small lung and pleural nodules and mediastinal lymphadenopathy, these findings were not conclusive for metastases. Whole-body fluorine-18 fluorodeoxyglucose positron emission tomography and CT (FDG-PET/CT) performed 15 days after right nephrectomy showed intense FDG uptake in the aforementioned lesions (lung and pleural nodules, mediastinal lymph nodes). Unexpectedly, focal increased FDG uptake was found in the right infraspinatus muscle. FDG-PET/CT was considered useful for evaluating distant metastases and thus portending the aggressive nature of sarcomatoid RCC.

Preoperative evaluation of perigastric vascular anatomy by 3-dimensional computed tomographic angiography using 16-channel multidetector-row computed tomography for laparoscopic gastrectomy in patients with early gastric cancer.

PURPOSE: The purpose of this study was to evaluate the efficacy of 3-dimensional computed tomographic angiography (3D CTA) using 16-channel multidetector-row helical computed tomography (MDCT) in the preoperative visualization of laparoscopic gastrectomy for early gastric cancer. MATERIALS AND METHODS: Twenty consecutive patients with early gastric cancer who underwent computed tomographic (CT) examination using 16-channel MDCT (0.625 mm x 16) before surgery were included in this study. At a rate of 4 mL/s, 2 mL/kg of 300 mg I/mL contrast material was intravenously injected. Timing for arterial phase scanning was determined by using a test bolus injection. Portal phase imaging was performed 70 seconds after the start of bolus injection. By using volume rendering and maximum intensity projection techniques, 3D CT angiograms of perigastric vessels were reconstructed from CT images of 0.625-mm thickness on computer workstations. RESULTS: In all cases, the left gastric artery (LGA) and the right gastric artery were correctly identified on 3D CTA, and the left gastric vein was also depicted on 3D CTA in all cases. In 2 cases, the aberrant left hepatic artery from LGA was correctly identified on 3D CTA. In 1 case, the accessory LGA from the left hepatic artery was correctly identified on 3D CTA. The variations of the veins included the left gastric vein flowing into the portal vein in 10 cases: the splenic vein in 9 and the junction of the portal and splenic veins in 1. CONCLUSIONS: A 3D CTA reconstructed from 16-channel MDCT images clearly revealed perigastric vascular anatomy in all cases, which is important for laparoscopic gastrectomy. Three-dimensional CTA is useful for the preoperative visualization of laparoscopic gastrectomy.

Clinical usefulness of the cardiac multi-detector-row CT.

Along with improvement of the temporal and special resolution, multi-detector-row CT has become able to generate artifact-less heart images. We discuss the potential benefits of the newly developed cardiac application, demonstrating informative cases.Two- and three-dimensional (2D and 3D) cardiac images were produced throughout one cardiac cycle. By paging 2D and 3D images in cardiac cycle order, animated movies were generated. Cardiac imaging with multi-detector-row CT, acquired during a single breath hold, provides information about: (1) clear morphology of heart chambers and myocardium, (2) wall motion and systolic thickening, (3) myocardial perfusion, (4) volume assessment, and (5) coronary anatomy and pathophysiology.

Intravenous three-dimensional CT portography using multi-detector row CT in patients with hepatic cirrhosis: evaluation of scan timing and image quality.

PURPOSE: To evaluate the scan timing and image quality of intravenous three-dimensional (3D) CT portography using multi-detector row CT (MDCT) and to assess the influence of patients' body weight on enhancement of the portal vein (PV). METHODS: One hundred nine patients with hepatic cirrhosis underwent triple-phase contrast enhanced CT using MDCT. The early, portal, and late phases were started at 30 sec, 60 sec, and 90 sec, respectively, after the beginning of intravenous injection of contrast medium (300 mgI/mL, 100 mL total). The CT value of the PV was assessed in the three phases: precontrast, portal phase, and late phase. 3D-portography of the MIP image was evaluated by three-point scale based on vessel visualization. The relationship between these data and body weight was investigated. RESULTS: The mean CT value of PV at 60 sec was 172.01+/-25.94 HU, which was significantly higher than that at 90 sec. Good or excellent 3D-CT portography was obtained in 97/109 patients (89%). Heavy patients tended to show less opacification of PV. CONCLUSIONS: Intravenous 3D-CT portography using MDCT at a 60 sec delay provided adequate PV images for patients with hepatic cirrhosis. Enhancement of PV was affected by patients' body weight.