Preclinical safety evaluation of Lipase OF from Candida cylindracea.

Triacylglycerol lipases are enzymes commonly used to process foods and beverages such as oils, wines, and cheeses through catalyzation of long-chain triglyceride hydrolysis. Lipase OF derived from Candida cylindracea (strain MS-5-OF) is only intended for use as a processing aid in food production applications; however, it may be present at trace levels in some products. As such, the safety of Lipase OF was evaluated in this study that included a bacterial reverse mutation assay, an in vitro chromosome aberration test, and a 90-day subchronic toxicity study in rats. In the in vitro bacterial reverse mutation and chromosome aberration assays, Lipase OF was not observed to be mutagenic at concentrations up to 5000 µg/plate and 50 µg/ml, respectively, in the presence or absence of metabolic activation. Results from the 90-day subchronic toxicity study indicated only minimal adverse effects (i.e., increased platelet count and prothrombin time) in male rats from the high-dose group following administration of Lipase OF via the diet at levels of 0, 1.0, 2.5, and 5.0 w/w%. The no-observed-adverse-effect level (NOAEL) for Lipase OF was therefore considered 2.5 w/w% (1597.6 mg/kg body weight/day [1027.3 mg TOS/kg body weight/day]) in males and 5.0 w/w% (3700.4 mg/kg body weight/day [2379.4 mg TOS/kg body weight/day]) in females under the test conditions. Thus, the evidence presented within this study supports the safe use of Lipase OF as a processing aid in various food production applications for human consumption.

Dual-Energy Computed Tomography for Evaluating Acute Brain Infarction of Middle Cerebral Artery Territories: Optimization of Voltage Settings in Virtual Monoenergetic Imaging.

OBJECTIVE: To evaluate the optimal virtual monochromatic energy in dual-energy computed tomography for differentiating between infarcted areas and normal brain parenchyma. METHODS: We enrolled 29 patients with middle cerebral artery acute brain infarction of who underwent examination by dual-energy computed tomography. We calculated the contrast-to-noise ratio (CNR) between white or gray matter and the infarcted area (CNR(W-I) and CNR(G-I), respectively) and normalized CNRs. From the normalized CNRs, we assessed which monochromatic energy gave the best balance between the infarcted area and normal brain parenchyma. The 70-keV images were used for comparison. RESULTS: The 99-keV images demonstrated the best balance between the infarction and normal brain parenchyma. In quantitative analysis, the 99-keV images were not inferior to the 70-keV images. (CNR(G-I), 1.92 ± 0.80 vs 2.00 ± 0.70, respectively [P = 0.16]; CNR(W-I), 0.52 ± 0.72 vs 0.40 ± 0.64, P < 0.01, respectively). CONCLUSIONS: Monochromatic 99-keV energy images may be optimal for evaluating middle cerebral artery acute brain infarction.

Magnetic resonance cholangiopancreatography with GRASE sequence at 3.0T: does it improve image quality and acquisition time as compared with 3D TSE?

OBJECTIVES: The current study evaluated the clinical usefulness of the gradient and spin-echo (GRASE) sequence with single breath-hold in 3.0 T magnetic resonance cholangiopancreatography (MRCP). We compared the acquisition time and image quality between GRASE and breath navigator-triggered 3D turbo spin echo (3D TSE). METHODS: We examined 54 consecutive patients who underwent MRCP with GRASE and 3D TSE. We compared the image acquisition time and contrast-to-noise ratio (CNR) between the common bile duct (CBD) and liver. Overall image quality, blurring, motion artifacts and CBD visibility were scored on a 4-point scale by two radiologists. Paired t-tests were used to compare the variables. RESULTS: The mean image acquisition time was 95 % shorter with the GRASE than with 3D TSE (GRASE: 20 s; 3D TSE: 6 min 27 s). The CNR of GRASE was significantly higher than that of 3D TSE (GRASE: 25.4 ± 13.9 vs. 3D TSE: 18.2 ± 9.6, p < 0.01). All qualitative scores for GRASE were significantly better than those for 3D TSE. CONCLUSIONS: 3.0 T MRCP with GRASE sequence with single breath-hold significantly improved the CNR of CBD with a 95 % shorter acquisition time compared with conventional 3D MRCP with 3D TSE. KEY POINTS: • MRCP acquisition time was 95% shorter with GRASE than with 3D TSE. • Overall image quality of GRASE was significantly better than 3D TSE. • Pancreaticobiliary tree visibility with GRASE was better than that with 3D TSE.

Brain computed tomography using iterative reconstruction to diagnose acute middle cerebral artery stroke: usefulness in combination of narrow window setting and thin slice reconstruction.

PURPOSE: The purpose of this study is to determine whether iterative model reconstruction (IMR) optimized for brain CT could improve the detection of acute stroke in the setting of thin image slices and narrow window settings. METHODS: We retrospectively reviewed 27 patients who presented acute middle cerebral artery (MCA) stroke. Images were reconstructed using filtered back projection (FBP; 1- and 5-mm slice thickness) and IMR (1 mm thickness), and contrast-to-noise ratios (CNRs) of infarcted and non-infarcted areas were compared. To analyze the performance of acute MCA stroke detection, we used receiver operating characteristic (ROC) curve techniques and compared 5-mm FBP with standard and narrow window settings, and 1-mm FBP and IMR with narrow window settings. RESULTS: The CNR in 1-mm IMR (1.1 ± 1.0) was significantly higher than in 5- (0.8 ± 0.7) and 1-mm FBP (0.4 ± 0.4) (p < 0.001). Furthermore, the average area under the ROC curve was significantly higher with 1-mm IMR with narrow window settings (0.90, 95% CI: 0.86, 0.94) than it was with 5-mm FBP (0.78, 95% CI: 0.72, 0.83). CONCLUSION: The combination of thin image slices and narrow window settings under IMR reconstruction provide better diagnostic performance for acute MCA stroke than conventional reconstruction methods.

Laparoscopic omental filling with intraoperative endoscopy for a perforated duodenal ulcer.

As a surgical treatment for a perforated duodenal ulcer, duodenal omental filling is effective. However, filling the perforation site with a sufficient amount of omentum is difficult in some situations. We herein report that we successfully filled a perforated duodenal ulcer with a sufficient amount of omentum using intraoperative endoscopy. The operation was performed with three ports, the operation time was 110 min, and the estimated blood loss was small. The postoperative course was good. No stenosis of deformity of the duodenum was observed on follow-up endoscopy. Laparoscopic surgery has a shorter operation time, shorter postoperative hospital stay, and less postoperative pain than open surgery. The combined use of intraoperative endoscopy with laparoscopic surgery is effective for a large perforation, and it can be expected to reduce the rate of conversion to open surgery. This combined procedure is considered useful as a laparoscopic omental filling operation.

Diagnosis of small posterior fossa stroke on brain CT: effect of iterative reconstruction designed for brain CT on detection performance.

OBJECTIVES: In this study, we aimed to determine whether iterative model reconstruction designed for brain CT (IMR-neuro) would improve the accuracy of posterior fossa stroke diagnosis on brain CT. METHODS: We enrolled 37 patients with ischaemic stroke in the posterior fossa and 37 patients without stroke (controls). Using axial images reconstructed using filtered back-projection (FBP) and IMR-neuro, we compared the CT numbers in infarcted areas, image noise in the pons, and contrast-to-noise ratios (CNRs) of infarcted and non-infarcted areas on scans subjected to IMR-neuro and FBP. To analyse the performance of hypo-attenuation detection, we used receiver-operating characteristic (ROC) curve techniques. RESULTS: The image noise was significantly lower (2.2 ± 0.5 vs. 5.1 ± 0.9 Hounsfield units, p < 0.01) and the difference in CNR between the infarcted and non-infarcted areas was significantly higher with IMR-neuro than with FBP (2.2 ± 1.7 vs. 4.0 ± 3.6, p < 0.01). Furthermore, the average area under the ROC curve was significantly higher with IMR-neuro (0.90 vs. 0.86 for FBP, p = 0.04). CONCLUSION: IMR-neuro yielded better image quality and improved hypo-attenuation detection in patients with ischaemic stroke. KEY POINTS: • Iterative model reconstruction of brain CT data can facilitate the diagnosis of ischaemic stroke. • IMR improved the detectability of low-contrast lesions in the posterior fossa. • IMR-neuro yielded better image quality and improved observer performance.

Iterative Reconstruction Designed for Brain CT: A Correlative Study With Filtered Back Projection for the Diagnosis of Acute Ischemic Stroke.

OBJECTIVES: The objective of this study is to evaluate the usefulness of iterative model reconstruction designed for brain computed tomography (CT) (IMR-Neuro) for the diagnosis of acute ischemic stroke. METHODS: This retrospective study included 20 patients with acute middle cerebral artery infarction who have undergone brain CT and 20 nonstroke patients (control). We reconstructed axial images with filtered back projection (FBP) and IMR-Neuro (slice thickness, 1 and 5 mm). We compared the CT number of the infarcted area, the image noise, contrast, and the contrast to noise ratio of the infarcted and the noninfarcted areas between the different reconstruction methods. We compared the performance of 10 radiologists in the detection of parenchymal hypoattenuation between 2 techniques using the receiver operating characteristic (ROC) techniques with the jackknife method. RESULTS: The image noise was significantly lower with IMR-Neuro [5 mm: 2.5 Hounsfield units (HU) ± 0.5, 1 mm: 3.9 HU ± 0.5] than with FBP (5 mm: 4.9 HU ± 0.5, 1 mm: 10.1 HU ± 1.4) (P < 0.01). The contrast to noise ratio was significantly greater with IMR-Neuro (5 mm: 2.6 ± 2.1, 1 mm: 1.6 ± 1.3) than with FBP (5 mm: 1.2 ± 1.0; 1 mm: 0.6 ± 0.5) (P < 0.01). The value of the average area under the receiver operating curve was significantly higher with IMR-Neuro than FBP (5 mm: 0.79 vs 0.74, P = 0.04; 1 mm: 0.76 vs 0.69, P = 0.04). CONCLUSIONS: Compared with FBP, IMR-Neuro improves the image quality and the performance for the detection of parenchymal hypoattenuation with acute ischemic stroke.

Usefulness of 3D hybrid profile order technique with 3T magnetic resonance cholangiography: Comparison of image quality and acquisition time.

PURPOSE: To evaluate the image quality and acquisition time of magnetic resonance cholangiopancreatography (MRCP) with and without the 3D hybrid profile order technique. MATERIALS AND METHODS: We studied 32 consecutive patients at 3T. They underwent MRCP with and without the 3D hybrid profile order imaging technique during free breathing and MRCP with the 3D hybrid profile order technique during a single breath-hold. The image acquisition time was 82% shorter with the 3D hybrid profile order technique than without it. The contrast, signal-to-noise-ratio (SNR), and contrast-noise-ratio (CNR) between the common bile duct (CBD) and periductal tissues on 3D-MRCP were evaluated quantitatively. RESULTS: The contrast, SNR, and CNR of the CBD under free breathing was significantly higher with the 3D hybrid profile order technique than without it (P < 0.01). The contrast, SNR, and CNR of the CBD under a single breath-hold was significantly higher with the 3D hybrid profile order technique than without it (P < 0.01). There were no significant differences in the contrast, SNR, and CNR of the CBD between the 3D hybrid profile order with a single breath-hold and with free breathing (P = 0.12, 0.28, 0.28, respectively). CONCLUSION: Using 3T MRI for MRCP with the 3D hybrid profile order sequence yielded significantly improved contrast and CNR with a shorter image acquisition time without sacrificing image quality when compared to imaging without the 3D hybrid profile order sequence. J. Magn. Reson. Imaging 2016;44:1346-1353.

Impact of Knowledge-Based Iterative Model Reconstruction in Abdominal Dynamic CT With Low Tube Voltage and Low Contrast Dose.

OBJECTIVE: The purpose of this study was to compare iterative model reconstruction (IMR) and hybrid iterative reconstruction (HIR) of 80-kVp abdominal dynamic CT scans obtained with a low-dose contrast agent. SUBJECTS AND METHODS: A group of 27 consecutively registered patients underwent abdominal dynamic CT with an 80-kVp protocol and a low dose of contrast agent (300 mg I/kg). Another 27 patients who had previously undergone a 120-kVp protocol with filtered back projection (FBP) and a standard contrast dose (600 mg I/kg) acted as control subjects. Effective dose, image noise, CT number, and contrast-to-noise ratio were compared between the 120-kVp and 80-kVp images with FBP, HIR, and IMR. Image contrast, image noise, image sharpness, noise texture, and overall image quality were evaluated for the four protocols. RESULTS: The effective dose of the 80-kVp protocol was lower than that with the 120-kVp protocol. The 80-kVp protocol with HIR and IMR decreased image noise by 45% and 70% compared with the 80-kVp protocol with FBP. The contrast-to-noise ratio of the 80-kVp protocol with IMR was higher than that of the 120-kVp protocol. Qualitatively, the 80-kVp protocol with IMR improved image noise more than the 120-kVp protocol did, but noise texture was worse. HIR and the 120-kVp protocol yielded similar subjective image quality. CONCLUSION: Use of the 80-kVp protocol with HIR allowed an approximately 50% reduction in contrast dose and an approximately 40% reduction in radiation dose compared with use of the 120-kVp protocol while preserving image quality. IMR reduced image noise more than HIR with this protocol but worsened noise texture.

Comparison of iterative model, hybrid iterative, and filtered back projection reconstruction techniques in low-dose brain CT: impact of thin-slice imaging.

INTRODUCTION: The purpose of this study was to evaluate the utility of iterative model reconstruction (IMR) in brain CT especially with thin-slice images. METHODS: This prospective study received institutional review board approval, and prior informed consent to participate was obtained from all patients. We enrolled 34 patients who underwent brain CT and reconstructed axial images with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and IMR with 1 and 5 mm slice thicknesses. The CT number, image noise, contrast, and contrast noise ratio (CNR) between the thalamus and internal capsule, and the rate of increase of image noise in 1 and 5 mm thickness images between the reconstruction methods, were assessed. Two independent radiologists assessed image contrast, image noise, image sharpness, and overall image quality on a 4-point scale. RESULTS: The CNRs in 1 and 5 mm slice thickness were significantly higher with IMR (1.2 ± 0.6 and 2.2 ± 0.8, respectively) than with FBP (0.4 ± 0.3 and 1.0 ± 0.4, respectively) and HIR (0.5 ± 0.3 and 1.2 ± 0.4, respectively) (p < 0.01). The mean rate of increasing noise from 5 to 1 mm thickness images was significantly lower with IMR (1.7 ± 0.3) than with FBP (2.3 ± 0.3) and HIR (2.3 ± 0.4) (p < 0.01). There were no significant differences in qualitative analysis of unfamiliar image texture between the reconstruction techniques. CONCLUSION: IMR offers significant noise reduction and higher contrast and CNR in brain CT, especially for thin-slice images, when compared to FBP and HIR.

Low-Contrast and Low-Radiation Dose Protocol in Cardiac Computed Tomography: Usefulness of Low Tube Voltage and Knowledge-Based Iterative Model Reconstruction Algorithm.

OBJECTIVE: This study aimed to evaluate the feasibility of a low contrast, low-radiation dose protocol of 80-peak kilovoltage (kVp) with prospective electrocardiography-gated cardiac computed tomography (CT) using knowledge-based iterative model reconstruction (IMR). METHODS: Thirty patients underwent an 80-kVp prospective electrocardiography-gated cardiac CT with low-contrast agent (222-mg iodine per kilogram of body weight) dose. We also enrolled 30 consecutive patients who were scanned with a 120-kVp cardiac CT with filtered back projection using the standard contrast agent dose (370-mg iodine per kilogram of body weight) as a historical control group. We evaluated the radiation dose for the 2 groups. The 80-kVp images were reconstructed with filtered back projection (protocol A), hybrid iterative reconstruction (HIR, protocol B), and IMR (protocol C). We compared CT numbers, image noise, and contrast-to-noise ratio among 120-kVp protocol, protocol A, protocol B, and protocol C. In addition, we compared the noise reduction rate between HIR and IMR. Two independent readers compared image contrast, image noise, image sharpness, unfamiliar image texture, and overall image quality among the 4 protocols. RESULTS: The estimated effective dose (ED) of the 80-kVp protocol was 74% lower than that of the 120-kVp protocol (1.4 vs 5.4 mSv). The contrast-to-noise ratio of protocol C was significantly higher than that of protocol A. The noise reduction rate of IMR was significantly higher than that of HIR (P < 0.01). There was no significant difference in almost all qualitative image quality between 120-kVp protocol and protocol C except for image contrast. CONCLUSIONS: A 80-kVp protocol with IMR yields higher image quality with 74% decreased radiation dose and 40% decreased contrast agent dose as compared with a 120-kVp protocol, while decreasing more image noise compared with the 80-kVp protocol with HIR.

Radiofrequency ablation combined with transarterial chemoembolization for intermediate hepatocellular carcinoma.

AIM: Radiofrequency ablation therapy (RFA) combined with transarterial chemoembolization (TACE) (combination therapy) is effective for early-stage hepatocellular carcinoma (HCC). The aim of this study was to compare the long-term effects of combination therapy with supportive care alone for intermediate HCC. METHODS: The study included 58 patients with intermediate HCC who received combination therapy (n = 34) or supportive care alone (n = 24). The inclusion criteria were a single nodule of more than 50 mm in diameter or two to three nodules, each measuring more than 30 mm in diameter, or more than three nodules, no vascular invasion and no extrahepatic metastasis. RESULTS: The overall survival rates at 1, 2, 3 and 5 years of the combination therapy group (91%, 65%, 53% and 27%, respectively) were significantly better (P < 0.0001) than those of the supportive care group (42%, 8%, 8% and 0%, respectively). Multivariate analysis identified treatment modality (combination therapy vs supportive care alone: P < 0.0001, risk ratio [RR] = 4.290 [95% confidence interval [CI] = 2.157-8.529]) and serum α-fetoprotein (P = 0.017, RR = 2.318 [95% CI = 1.166-4.610]) as independent and significant factors of overall survival. CONCLUSION: The combination of TACE and RFA is a safe and effective therapy in patients with intermediate HCC.

Novel contrast-injection protocol for coronary computed tomographic angiography: contrast-injection protocol customized according to the patient's time-attenuation response.

We developed a new individually customized contrast-injection protocol for coronary computed tomography (CT) angiography based on the time-attenuation response in a test bolus, and investigated its clinical applicability. We scanned 60 patients with suspected coronary diseases using a 64-detector CT scanner, who were randomly assigned to one of two protocols. In protocol 1 (P1), we estimated the contrast dose to yield a peak aortic attenuation of 400 HU based on the time-attenuation response to a small test-bolus injection (0.3 ml/kg body weight) delivered over 9 s. Then we administered a customized contrast dose over 9 s. In protocol 2 (P2), the dose was tailored to the patient's body weight; this group received 0.7 ml/kg body weight with an injection duration of 9 s. We compared the two protocols for dose of contrast medium, peak attenuation, variations in attenuation values of the ascending aorta, and the success rate of adequate attenuation (250-350 HU) of the coronary arteries. The contrast dose was significantly smaller in P1 than in P2 (36.9 ± 9.2 vs 43.1 ± 7.0 ml, P < 0.01). Peak aortic attenuation was significantly less under P1 than under P2 (384.1 ± 25.0 vs 413.5 ± 45.7, P < 0.01). The mean variation (standard deviation) of the attenuation values was smaller in P1 than in P2 (25.0 vs 45.7, P < 0.01). The success rate of adequate attenuation of the coronary arteries was significantly higher with P1 than with P2 (85.0 vs 65.8 %, P < 0.01). P1 facilitated a reduction in the contrast dose, reduced the individual variations in peak aortic attenuation, and achieved optimal coronary CT attenuation (250-350 HU) more frequently than P2.

Contrast material and radiation dose reduction strategy for triple-rule-out cardiac CT angiography: feasibility study of non-ECG-gated low kVp scan of the whole chest following coronary CT angiography.

BACKGROUND: Dedicated coronary computed tomography (CT) scan has been proven to be an accurate diagnostic modality in evaluating coronary artery disease. A second phase scan starting immediately after the coronary CT scan might enable visualization of the different vascular territories of the entire chest. PURPOSE: To investigate the feasibility of a contrast material and radiation dose reduction triple-rule-out (TRO) CT angiography (CTA) protocol with serial non-ECG-gated low kVp scan of the whole chest, which utilizes a recirculated contrast agent. MATERIAL AND METHODS: Thirty patients were scanned with the new TRO-CTA protocol; after the coronary scan with retrospective ECG-gating, non-ECG-gated whole-chest CTA was performed at 80 kVp to evaluate aortic arch (AAr) and pulmonary trunk (PT). Another 30 patients were scanned by our conventional TRO-CTA protocol at 120 kVp with retrospective ECG-gating. We compared the estimated effective dose (ED), contrast material (CM) dose, contrast-to-noise ratio (CNR) of the ascending aorta (AAo), and the rate of patients who could achieve adequate attenuation of the AAr and PT between the two protocols. RESULTS: The total ED of the new TRO-CTA protocol was 29.6% lower than that of the conventional protocol (P < 0.01). The amount of CM used for the new TRO-CTA protocol was significantly lower than in the conventional protocol (60.1 ± 9.6 mL vs. 91.8 ± 22.6 mL, P < 0.01). The CNR of the AAo was 30.2% higher with the new TRO-CTA protocol than with the conventional protocol (P < 0.01). There was no significant difference in the success rate of adequate attenuation of the AAr and PT between the two protocols (P > 0.05). CONCLUSION: The new TRO-CTA protocol can reduce the total dose of radiation and the contrast dose and yield adequate vascular enhancement compared with the conventional protocol.

Low-contrast-dose protocol in cardiac CT: 20% contrast dose reduction using 100 kVp and high-tube-current-time setting in 256-slice CT.

BACKGROUND: The use of the smallest contrast dose is highly desirable in performing cardiac computed tomography (CT), especially for patients with cardiovascular diseases to prevent contrast-induced nephropathy. PURPOSE: To evaluate the feasibility of 20% reduced contrast dose protocol in cardiac CT using 100 kVp and high-tube-current-time product setting. MATERIAL AND METHODS: Fifty patients were scanned with our conventional 120 kVp protocol, and the other 50 patients underwent scans using a tube voltage of 100 kVp, a high-tube-current-time product, and a 20% reduced contrast dose. We evaluated estimated effective dose (ED), CT attenuation, image noise, and contrast-to-noise ratio (CNR) of the ascending aorta. We also evaluated CT attenuation of the coronary arteries. Two radiologists independently assessed image quality of coronary arteries. RESULTS: There was no significant difference in the ED between the 100 kVp and 120 kVp protocols (21.7 mSv ± 1.6 vs. 21.8 mSv ± 1.1, P=0.65). There was no significant difference in the CNR of the ascending aorta between the 100 kVp and 120 kVp protocols (18.8 ± 3.5 vs. 18.7 ± 3.8, P=0.98). Mean CT attenuation of the coronary arteries of the 100 kVp protocols was significantly higher than that of 120 kVp protocols (P<0.05). There was no significant difference in the overall image quality of the coronary artery between the 100 kVp and 120 kVp protocols (3.7 ± 0.4 vs. 3.7 ± 0.5, P=0.65). CONCLUSION: For cardiac CT a voltage setting of 100 kVp and a high-tube-current-time product enable 20% reduction in the contrast dose without affecting the quality of coronary artery images compared with a 120 kVp and standard-contrast-dose CT protocol.

Usefulness of the SPACE pulse sequence at 1.5T MR cholangiography: comparison of image quality and image acquisition time with conventional 3D-TSE sequence.

PURPOSE: To prospectively evaluate the image quality and image acquisition time at 3D magnetic resonance cholangiopancreatography (MRCP) using sampling perfection with application optimized contrasts (SPACE) and conventional turbo-spin-echo (TSE) sequences. MATERIALS AND METHODS: We acquired navigator-triggered SPACE and conventional 3D-TSE MRCP images using the same parameters where possible for 30 patients and compared the image acquisition time, contrast, and contrast-to-noise ratio (CNR) of the common bile duct (CBD). Two radiologists performed qualitative analyses using a 4-point scale. RESULTS: Image acquisition time was 31% shorter with the SPACE than the conventional TSE sequence (248.9 ± 73.0 sec vs. 360.5 ± 99.9 sec, P < 0.01). The contrast and CNR was significantly higher with the SPACE technique than conventional TSE (39.4 ± 14.7 vs. 33.5 ± 14.2, P < 0.01 and 18.6 ± 7.8 vs. 15.5 ± 9.3, P = 0.03). All visual scores were higher for the SPACE than the conventional TSE sequence; there was a significant difference in motion artifacts and the depiction of the CBD and the left hepatic and main pancreatic duct (P < 0.05). CONCLUSION: On the 1.5T MR scanner, 3D-MRCP with the SPACE sequence significantly improved the contrast and CNR of CBD. In addition, it yielded images of better quality at 30% shorter acquisition time than constant refocusing pulse flip angle TSE.

Timing of the hepatic arterial phase at Gd-EOB-DTPA-enhanced hepatic dynamic MRI: comparison of the test-injection and the fixed-time delay method.

PURPOSE: To compare the fixed-time- and the test-injection method with respect to the image quality of hypervascular hepatocellular carcinoma (HCC) and the adequacy of timing of the hepatic arterial phase (HAP) in Gd-EOB-DTPA (EOB) enhanced MRI. MATERIALS AND METHODS: We studied 63 patients with computed tomography (CT) -proven hypervascular HCC: 30 (group 1) were scanned HAP using the fixed-time delay method (protocol 1); in the other 33 (group 2), we applied the test-injection method (protocol 2). We compared the protocols with respect with tumor-to-liver contrast (TLC), contrast-to-noise-ratio (CNR), and relative enhancement of the liver and tumor (REL , RET ) during HAP. Two radiologists compared the adequacy of HAP, image contrast, image noise, and overall image quality. RESULTS: Under protocol 2, TLC, CNR, and REL and RET of hypervascular HCC were significantly higher (P < 0.01). The proportion of optimal HAP was significantly higher for protocol 2 than protocol 1 (P < 0.01). The visual score of the image contrast and the overall image quality were significantly higher in group 2 than group 1 (P = 0.02 and P = 0.01, respectively). CONCLUSION: At EOB-enhanced hepatic dynamic MRI, the test-injection method yielded better image quality of hypervascular HCC and improved adequacy of timing of HAP.

Subtracted 3D CT angiography for the evaluation of intracranial aneurysms in 256-slice multidetector CT: usefulness of the 80-kVp plus compact contrast medium bolus protocol.

OBJECTIVES: To evaluate the usefulness of an 80-kVp and compact contrast material protocol for arterial phase subtracted cerebral 3D-CTA using 256-slice multidetector CT. METHODS: Thirty-two patients underwent CT with 100 kVp and received a contrast dose of 370 mgI/kg body weight over 15 s (protocol A). Thirty-three patients underwent CT with 100 kVp and received a contrast dose of 296 mgI/kg body weight over 10 s (protocol B). Thirty-three other patients underwent CT with 80 kVp and received a contrast medium dose of 296 mgI/kg body weight over 10 s (protocol C). We compared the arterial attenuation and contrast noise ratio (CNR) of each protocol. Two independent readers assessed overall image quality. RESULTS: Arterial attenuation was significantly higher under protocols A (418.6 ± 71.1 HU) and C (442.7 ± 79.3 HU) than under protocol B (355.8 ± 107.2 HU; P < 0.05). The CNR of protocol C (26.1 ± 6.1) was higher than that of protocol A (20.7 ± 8.4; P < 0.05). The overall image quality of protocol A was higher than that of protocol C (P < 0.01). CONCLUSION: The 80-kVp plus compact contrast protocol is well suited to arterial phase subtracted cerebral 3D-CTA without confounding venous enhancement. KEY POINTS: • Subtracted 3D CT angiography is useful in the evaluation of intracranial aneurysms. • A compact contrast material protocol increased arterial attenuation without venous contamination. • Low-kVp CT compensated for the decreased amount of contrast medium. • An 80-kVp CT with a compact enhancement bolus provides good intracranial 3D-CT angiography.

Novel connecting tube for saline chaser in contrast-enhanced CT: the effect of spiral flow of saline on contrast enhancement.

OBJECTIVE: To evaluate the effect of a newly developed connecting tube, which generates a spiral flow of saline, on aortic and hepatic contrast enhancement during hepatic-arterial phase (HAP) and portal venous phase (PVP) computed tomography (CT). METHODS: Eighty patients were randomly assigned to one of two protocols: with a new or a conventional tube. The contrast material (600 mgI/kg) was delivered over 30 s; this was followed by the administration of 25 ml saline solution delivered at the same injection rate as the contrast material. Unenhanced and contrast-enhanced CT images of the upper abdomen were obtained. We calculated the changes in the CT number (∆HU) for the aorta during HAP and PVP, and for the liver during PVP. We compared ∆HU between protocols. RESULTS: The mean ∆HU for the abdominal aorta during HAP was significantly higher with the new tube protocol than with the conventional tube protocol (322 ± 53 vs. 290 ± 53, P < 0.01). There were no significant differences in the mean ∆HU for the abdominal aorta and liver during PVP between the two protocols (P > 0.05). CONCLUSION: The new connecting tube increased the effect of a saline chaser and significantly improved aortic enhancement during HAP. KEY POINTS: • Optimal administration of intravenous contrast material is essential for optimal CT quality. • A new connecting tube can generate spiral flow, which improves intravenous administration. • The new connecting tube improved aortic contrast enhancement during the hepatic-arterial phase. • The new connecting tube increased the effect of a saline chaser.

Contrast enhancement during hepatic computed tomography: effect of total body weight, height, body mass index, blood volume, lean body weight, and body surface area.

OBJECTIVE: The objective of this study was to evaluate the effect of total body weight, height, body mass index, blood volume, lean body weight, and body surface area (BSA) on aortic and hepatic contrast enhancement during hepatic computed tomography (CT). METHODS: We calculated the changes in the CT number per gram of iodine ((Δ Hounsfield units/g [ΔHU/g])) for the aorta and the liver during portal venous phase. We performed linear regression analyses between ΔHU/g and each of the body parameters. RESULTS: ΔHU/g and BSA showed the strongest inverse correlation. The correlation coefficients for the aorta and liver were 0.70 and 0.68 for ΔHU/g and total body weight, 0.41 and 0.37 for height, 0.54 and 0.55 for body mass index, 0.68 and 0.59 for blood volume, 0.70 and 0.62 for lean body weight, and 0.71 and 0.68 for BSA, respectively (P < 0.001 for all). CONCLUSION: Our study supports the use of a protocol with iodine dose adjusted for the patient BSA.