Prediction of Posthepatectomy Liver Failure: MRI With Hepatocyte-Specific Contrast Agent Versus Indocyanine Green Clearance Test.

OBJECTIVE: The objective of our study was to identify whether quantitative measurements from gadoxetic acid-enhanced MRI are useful for predicting posthepatectomy liver failure (PHLF) in patients with hepatocellular carcinoma (HCC) compared with and in combination with future remnant liver volume (FRLV) and an indocyanine green (ICG) clearance test. MATERIALS AND METHODS: Preoperative gadoxetic acid-enhanced MR images were retrospectively evaluated in 73 patients who underwent anatomic liver resection for HCC between 2011 and 2013. For quantitative measurement of hepatocyte function, relative liver enhancement (RLE) and remnant hepatocyte uptake index (rHUI) were measured using hepatobiliary phase MR images. FRLV was determined using measurements from preoperative CT scans. Univariate and multivariate analyses of measurements from gadoxetic acid-enhanced MRI, ICG clearance tests, and FRLV for finding predictors of PHLF were performed. To compare the diagnostic performance of predictors, ROC analyses were also performed. RESULTS: Eighteen (25%) of 73 patients met the criteria for PHLF. Univariate analysis revealed that all measurements related to MRI including RLE, rHUI, ICG clearance, and FRLV were significantly associated with PHLF. Multivariate analysis showed that RLE, FRLV, ICG-plasma disappearance rate (ICG-PDR), rHUI, and rHUI corrected for body weight (rHUI-BW) were independent predictors of PHLF (p = 0.011, p = 0.034, p = 0.003, p < 0.001, and p = 0.001, respectively). In ROC analyses, AUCs of rHUI and rHUI-BW were larger than those of other independent predictors; the differences were statistically significant (for rHUI-BW vs RLE, ICG-PDR, and FRLV, p = 0.016, 0.007, and 0.046, respectively; for rHUI vs RLE and ICG-PDR, p = 0.045 and 0.016, respectively). CONCLUSION: Measurements from gadoxetic acid-enhanced MRI predicted PHLF better than the ICG clearance test in patients with HCC who underwent hepatectomy.

Computed Diffusion Weighted Imaging of the Liver Using Extrapolation Technique in Patients Who Underwent Liver Transplantation With Hepatocellular Carcinomas: Initial Experience and Feasibility Study.

OBJECTIVE: This study aimed to evaluate the feasibility and image quality of computed diffusion weighted imaging (DWI) of the liver in patients with hepatocellular carcinoma (HCC). METHODS: Twenty-four patients who underwent liver transplantation with HCC were enrolled. Computed DWI was synthesized for b-values of 800 (cDWI800) and 1200 s/mm (cDWI1200) using directly acquired DWI with b-values of 0, 50, and 500 s/mm. Signal intensity of HCC, background liver, and contrast-to-noise ratio were evaluated for directly acquired DWI of 800 s/mm (dDWI800), cDWI800, and cDWI1200. Two radiologists evaluated the image quality for contrast between HCC and liver, suppression of background signal and T2 shine-through, and overall image quality. RESULTS: cDWI1200 showed the lowest contrast-to-noise ratio. Qualitative scores for background suppression and decreased T2 shine-through were highest for cDWI1200. However, contrast between HCC and background liver was worst in cDWI1200. CONCLUSIONS: In computed DWI of high b-values, contrast between HCC and background liver was very low.

MRI of Small Hepatocellular Carcinoma: Typical Features Are Less Frequent Below a Size Cutoff of 1.5 cm.

OBJECTIVE: The purposes of this study were to analyze MRI features of small hepatocellular carcinomas (HCCs) on the basis of size and to evaluate the difference in frequency of typical radiologic hallmarks of HCC (arterial enhancement and washout) according to the tumor size. MATERIALS AND METHODS: Enrolled were 86 patients with 110 HCCs 3 cm or smaller who underwent surgical resection or transplantation. Two radiologists reviewed gadoxetic acid-enhanced MRI features for signal intensity of T2-weighted and T1-weighted imaging, diffusion restriction, presence of arterial enhancement, washout on portal and transitional phases, and signal intensity on the hepatobiliary phase. ROC curve analysis was performed to determine the optimal HCC cutoff size for radiologic hallmarks of HCC. Tumors were divided into two groups by cutoff size, and the frequencies of MRI features were assessed. RESULTS: On ROC analysis, the optimal cutoff for radiologic hallmarks of HCC was 1.5 cm in independent and consensus reviews by two radiologists. HCCs smaller than 1.5 cm showed typical finding of HCC less frequently than HCCs 1.5 cm or larger in diameter. In subgroup analyses, HCCs with diameters between 1 and 1.5 cm showed similar MRI findings to HCCs with diameters 1 cm or less but significantly different findings compared with HCCs with diameters from 1.5 to 2 cm and 2-3 cm. CONCLUSION: HCCs smaller than 1.5 cm in size less frequently showed MRI findings seen typically in larger HCCs. Therefore, small HCCs are harder to detect with certainty not only because of small size but also because of the lower frequency of typical MRI findings.

Performance of Gadoxetic Acid-Enhanced Liver Magnetic Resonance Imaging for Predicting Patient Eligibility for Liver Transplantation Based on the Milan Criteria.

PURPOSE: This study aimed to evaluate the accuracy of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) in predicting eligibility for liver transplantation in patients with hepatocellular carcinoma (HCC) based on Milan criteria (MC). MATERIALS AND METHODS: We reviewed Gd-EOB-MRI of 44 patients who underwent liver transplantation for HCC with cirrhosis for the presence/size of HCCs, vascular invasion, and transplant eligibility based on MC. Hepatocellular carcinoma was diagnosed based on conventional radiological hallmarks (arterial enhancement and washout) or the modified criteria. RESULTS: Among 44 patients, 16 was beyond MC. Sensitivity, specificity, and accuracy of conventional radiological hallmark and the modified criteria for predicting eligibility by MC were 31.3%, 96.3%, and 72.7%, and 68.8%, 96.3%, and 86.4%, respectively. CONCLUSIONS: Gd-EOB-MRI showed high specificity but poor sensitivity for assessing transplant eligibility based on MC when adopting the conventional radiological hallmarks of HCC. Our modified criteria showed significantly better sensitivity and accuracy than the conventional radiological hallmarks.

Patient Dose Management: Focus on Practical Actions.

Medical radiation is a very important part of modern medicine, and should be only used when needed and optimized. Justification and optimization of radiation examinations must be performed. The first step of reduction of medical exposure is to know the radiation dose in currently performed examinations. This review covers radiation units, how various imaging modalities report dose, and the current status of radiation dose reports and legislation. Also, practical tips that can be applied to clinical practice are introduced. Afterwards, the importance of radiology exposure related education is emphasized and the current status of education for medical personal and the public is explained, and appropriate education strategies are suggested. Commonly asked radiation dose related example questions and answers are provided in detail to allow medical personnel to answer patients. Lastly, we talk about computerized programs that can be used in medical facilities for managing patient dose. While patient dose monitoring and management should be used to decrease and optimize overall radiation dose, it should not be used to assess individual cancer risk. One must always remember that medically justified examinations should always be performed, and unneeded examinations should be avoided in the first place.

Radiation Doses of Various CT Protocols: a Multicenter Longitudinal Observation Study.

Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiation doses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiation dose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiation dose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiation doses were decreased during the 3 years. This study showed the effects of decreased CT radiation dose by efforts of radiologists and medical society.

SLAP tears: diagnosis using 3-T shoulder MR arthrography with the 3D isotropic turbo spin-echo space sequence versus conventional 2D sequences.

OBJECTIVES: The aim of this study was to determine the accuracy and reliability of shoulder magnetic resonance (MR) arthrography with three-dimensional (3D) isotropic intermediate-weighted turbo spin-echo (TSE) sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) in the diagnosis of superior labrum anterior-to-posterior (SLAP) lesions compared with two-dimensional (2D) TSE at 3.0 T. METHODS: MR arthrograms, including 2D TSE and 3D TSE-SPACE, in 87 patients who underwent arthroscopy were retrospectively analysed by two reviewers for the presence and type of SLAP lesions. Sensitivity and specificity were compared using McNemar's test, and inter-observer agreement was calculated using Cohen's kappa. Receiver operating characteristic (ROC) curve analyses were performed. RESULTS: The mean sensitivity, specificity and accuracy were 90%, 85% and 86% for 2D TSE, and 81%, 86% and 85% for 3D TSE-SPACE respectively, with no statistically significant differences. Inter-observer agreements were substantial in 2D TSE (κ = 0.76) and 3D TSE-SPACE (κ = 0.68). The areas under the ROC curves were 0.92 for 2D TSE and 0.90 for 3D TSE-SPACE, which were not significantly different. CONCLUSIONS: MR arthrography with 3D TSE-SPACE showed comparable accuracy and substantial inter-observer agreement for the diagnosis of SLAP lesions.

Effect of beam-flow angle on velocity measurements in modern Doppler ultrasound systems.

OBJECTIVE: The purpose of this article is to examine the effect of different beam-flow angles on the accuracy of Doppler ultrasound velocity measurements in modern ultrasound systems. MATERIALS AND METHODS: A flow phantom was used to create a steady flow of water in a 4.3-mm-diameter tube. Using three different modern university-grade ultrasound systems, flow was measured at 30°, 40°, 50°, 60°, 70°, 80°, and 88° beam-flow angles twice by two radiologists in consensus using a convex and linear probe. Measured flow ratio, defined as measured velocity divided by estimated actual velocity, was calculated. Intraprobe, interprobe, and intermachine mean variation of measured flow ratio were calculated. RESULTS: Measured flow ratio increased as beam-flow angles increased. Measured flow ratios for the angles 30°, 40°, 50°, 60°, 70°, 80°, and 88° were 0.90, 0.97, 1.10, 1.22, 1.62, 2.34, and 10.29, respectively. Intraprobe, interprobe, and intermachine variation did not show marked differences. For angles grouped as 30-40°, 50-60°, 70°, and 80-88°, intraprobe variation was 12%, 15%, 15%, and 26%; interprobe variation was 20%, 16%, 13%, and 26%; and intermachine variation was 16%, 16%, 17%, and 54%, respectively. As beam-flow angle increased, an increase in spectral broadening was also noted. CONCLUSION: There is no simple cutoff beam-flow value, such as the well-quoted less than 60°, at which velocity measurements can be considered accurate. For follow-up imaging, beam-flow angle differences should be considered, and the same beam-flow angles should be used when possible. Follow-up imaging by different sonography machines is feasible.

What radiologists want to see: stack mode display in PowerPoint.

OBJECTIVE: The purpose of this article is to describe a stack mode viewer that is fully embeddable in PowerPoint and does not require external files. CONCLUSION: We developed a Web-based service named "RadViewer" that creates a Flash-based stack mode viewer and that is automatically embedded into PowerPoint. Features include mouse wheel and keyboard scrolling, zoom, cine loop, and brightness and contrast controls similar to those of a PACS workstation. Stack mode viewer created by RadViewer can be used in most radiology society meetings and conferences that use PowerPoint.

Preliminary experience using high intensity focused ultrasound for treating liver metastasis from colon and stomach cancer.

PURPOSE: To determine the efficacy and safety from our preliminary results of using high intensity focused ultrasound (HIFU) to treat liver metastasis from colon and stomach cancer. MATERIALS AND METHODS: Ten patients with liver metastasis from colon cancer and three from stomach cancer underwent HIFU under general anesthesia. HIFU was performed using an extracorporeal, ultrasound-guided focused system. Complications during the study, extent of coagulative necrosis at two-week follow up, and evidence of tumor on further follow up were analyzed. Patients were divided into four categories: (I) complete ablation with no evidence of recurrence on follow up; (II) apparent complete ablation of target mass with new foci of disease in the target organ or distant malignancy and no local tumor progression; (III) local tumor progression after apparent complete ablation; (IV) partial ablation. RESULTS: Mean follow-up period was 22 weeks in the colon cancer group and 58 weeks in the stomach cancer group. The sum of total lesion size was between 1.8 cm and 21.4 cm (mean: 8.4 cm +/- 6.7 cm) for the colon cancer group and between 1.7 and 16.3 cm (mean: 8.8 cm +/- 7.3 cm) for the stomach cancer group. In the colon cancer group, one patient was categorized as category I, one as category II, three as category III, and the remaining five as category IV. The stomach cancer group showed two patients as category I, and one as category II. CONCLUSION: For treating liver metastasis from colon and stomach cancer HIFU seems safe but its efficacy is questionable. Further research is warranted.

F-18 FDG PET/CT demonstration of thymoma followed by development of lung cancer.

It is well-known that thymoma can be associated with diverse extrathymic malignancies. The authors present a case of a 72-year-old man with myasthenia gravis in which F-18 FDG PET/CT demonstrated high FDG uptake in both an anterior mediastinal mass and a lung nodule. The FDG uptake in the lung nodule was significantly higher than that of the thymic lesion, which might suggest the possibility of a second development of lung cancer in this thymoma patient. Surgical resection was done for the 2 tumors, and histologic examination revealed anterior mediastinal thymoma and primary adenocarcinoma of the lung. This case demonstrates the potential usefulness of PET/CT in detecting and assessing the second extrathymic malignancy in a patient with thymoma.

The Diagnostic Performance of Liver MRI without Intravenous Contrast for Detecting Hepatocellular Carcinoma: A Case-Controlled Feasibility Study.

Objective: To preliminarily evaluate the diagnostic performance of an unenhanced MRI for detecting hepatocellular carcinoma (HCC) with a case-control study design. Materials and Methods: The case group consisted of 175 patients with initially-diagnosed HCC, who underwent a 3T liver MRI. A total of 237 HCCs were identified. The number of HCCs that were smaller than 1 cm, 1 cm ≤ and < 2 cm, and ≥ 2 cm were 19, 105, and 113, respectively. For the control group, 72 patients with chronic liver disease, who did not have HCC, were enrolled. Two radiologists independently reviewed the T2 half-Fourier acquisition single-shot turbo spin echo, T2 fast spin echos with fat saturation, T1 gradient in- and out-of-phase images, and diffusion-weighted images/apparent diffusion coefficient maps to detect HCC. Per-patient analyses were performed to evaluate the sensitivity and specificity of the non-contrast MRI for diagnosing HCC. Furthermore, the per-lesion sensitivity was also calculated according to tumor size. Results: In the per-patient analyses, the sensitivity and specificity of reader 1 were 86.3% (151/175) and 87.5% (63/72), respectively; while those of reader 2 were 82.9% (145/175) and 76.4% (55/72), respectively. When excluding HCCs smaller than 1 cm, the sensitivity of reader 1 and 2 were 88.0% (147/167) and 86.2% (144/167), respectively. In the per-lesion analyses, the sensitivities of reader 1 and reader 2 were 75.9% (180/237) and 70.5% (167/237), respectively. Conclusion: The per-patient sensitivity and specificity of non-contrast MRIs were within a reasonable range for the initial diagnosis of HCC. Non-contrast MRIs may have a potential for surveillance of HCC. Further confirmatory diagnostic test accuracy studies are needed.

Reproducibility of mRECIST in Measurement and Response Assessment for Hepatocellular Carcinoma Treated by Transarterial Chemoembolization.

RATIONALE AND OBJECTIVES: To evaluate the reproducibility of Modified Response Evaluation Criteria in Solid Tumors (mRECIST) for hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE) using multiphasic computed tomography. MATERIALS AND METHODS: The institutional review board approved this retrospective study. We evaluated 97 patients who underwent TACE (60 conventional TACE [cTACE] and 37 drug-eluting bead TACE [DEB-TACE]) for HCC from 2010 to 2014. Four radiologists evaluated pairs of dynamic liver CTs scanned within 2 months before and after TACE based on mRECIST. Assessment of intra- or interobserver reproducibility for response categorization and sum of long diameter were evaluated using weighted kappa statistics (κ) and intraclass correlation coefficients, respectively. The relationship between concordance of target lesion selection and agreement of target lesion response was evaluated using Fisher exact test. RESULTS: Intraobserver reproducibility for overall response was moderate to excellent (κ = 0.525-0.865). Interobserver reproducibility was improved on the second review compared to the first review and it was good in both treatment groups (κ = 0.627 for cTACE and 0.602 for DEB-TACE). Between the two treatment methods, intra- or interobserver reproducibility was better after cTACE than DEB-TACE. Intraclass correlation coefficients for sum of long diameter measurement showed excellent intra- or interobserver reproducibility. The concordance rate of target lesion selection was significantly higher for patients with radiologists' agreement for target lesion response than patients with disagreed response (P = .003). CONCLUSIONS: The intra- and interobserver reproducibility of mRECIST in patients with HCC after TACE was moderate to excellent, and the reproducibility was slightly better after cTACE than DEB-TACE.

Validation of intimate correlation between visceral fat and hepatic steatosis: Quantitative measurement techniques using CT for area of fat and MR for hepatic steatosis.

BACKGROUND & AIM: The relationship between obesity and hepatic steatosis is well known, and there are many methods to measure obesity and severity of hepatic steatosis. Because of advances in radiologic techniques, the areas of certain body components can be measured on computed tomography (CT) while the severity of hepatic steatosis can be measured by magnetic resonance spectroscopy (MRS) with high accuracy. The aim of this study is to investigate the relationship between degree of fatty infiltration of the liver measured by MRS and body composition measured from CT images. MATERIALS AND METHODS: We evaluated 95 potential liver donors who underwent abdomen CT and liver MRI (including MRS) between February 2014 and September 2015 in a tertiary university hospital. Body composition analysis was performed on CT images using commercial software. The areas of subcutaneous fat, visceral fat and abdominal circumference were measured automatically and the area of muscle was measured semi-automatically. The degree of hepatic steatosis was measured by MRS. RESULTS: The degree of hepatic steatosis showed a significant correlation with total fat area, visceral fat area, subcutaneous fat area, muscle area, abdominal circumference, BMI, and ratio of visceral fat to total fat. The strongest correlation was between hepatic steatosis and the area of visceral fat in all subjects (r=0.569). Multivariate regression analysis showed that male gender and visceral fat area were significantly associated with hepatic steatosis (P = 0.031, <0.001, respectively). CONCLUSIONS: The area of visceral fat has the most intimate correlation to the severity of hepatic steatosis among all significantly correlated parameters associated with body habitus. Accurate and quantitative body composition measurement and degree of hepatic steatosis can be noninvasively performed using advanced radiological techniques.

Pancreatic hardness: Correlation of surgeon's palpation, durometer measurement and preoperative magnetic resonance imaging features.

AIM: To evaluate the correlation between subjective assessments of pancreatic hardness based on the palpation, objective measurements using a durometer, and magnetic resonance imaging (MRI) findings for assessing pancreatic hardness. METHODS: Eighty-three patients undergoing pancreatectomies were enrolled. An experienced surgeon subjectively evaluated the pancreatic hardness in the surgical field by palpation. The pancreatic hardness was also objectively evaluated using a durometer. Preoperative MRI findings were evaluated by a radiologist in terms of the apparent diffusion coefficient (ADC) values, the relative signal intensity decrease (RSID) of the pancreatic parenchyma, and the diameter of the pancreatic parenchyma and duct. Durometer measurement results, ADC values, RSID, pancreatic duct and parenchyma diameters, and the ratio of the diameters of the duct and parenchyma were compared between pancreases judged to be soft or hard pancreas on the palpation. A correlation analysis was also performed between the durometer and MRI measurements. RESULTS: The palpation assessment classified 44 patients as having a soft pancreas and 39 patients as having a hard pancreas. ADC values were significantly lower in the hard pancreas group. The ductal diameter and duct-to-pancreas ratio were significantly higher in the hard pancreas group. For durometer measurements, a correlation analysis showed a positive correlation with the ductal diameter and the duct-to-pancreas ratio and a negative correlation with ADC values. CONCLUSION: Hard pancreases showed lower ADC values, a wider pancreatic duct diameter and a higher duct-to-pancreas ratio than soft pancreases. Additionally, the ADC values, diameter of the pancreatic duct and duct-to-pancreas ratio were closely correlated with the durometer results.

The effect of different methods of intravenous injection on glass particle contamination from ampules.

There have been many studies on glass particle contamination from glass ampules during the injection of glass ampules, but only the contamination from direct IV bolus injection has been measured. This research aimed to study the difference in glass particle contamination from ampules with different intravenous administration methods commonly used in clinical practice. Four methods were studied: IV bolus injection directly after immediate aspiration, IV bolus injection directly after 2 min' delayed aspiration, IV bolus injection directly after aspiration with a filter needle, and side shooting to an infusion set with an in-line filter. 45 ampules per method for a total of 180 ampules were used. The number and length of glass particles were measured using a slide scanner. Aspiration was performed without specifically using a slow aspiration method. The longest glass particle was observed in the immediate aspiration group. The side shooting group showed the lowest maximum number of glass particles per ampule. The side shooting group also showed the smallest number of glass particles, but it was statistically insignificant. Using a filter needle syringe and 2 min' delayed aspiration, which are frequently recommended to minimize contamination, may not be as effective as commonly believed, unless combined with a slow and low pressure aspiration method. Using a side shooting to an infusion set with an in-line filter may minimize glass particle contamination from ampules even without a slow and low pressure aspiration method, but more evidence from a larger study is needed.