The World Federation for Ultrasound in Medicine and Biology has produced these guidelines for the use of elastography techniques in liver diseases. For each available technique, the reproducibility, ...results and limitations are analyzed, and recommendations are given. This set of guidelines updates the first version, published in 2015. Since the prior guidelines, there have been several advances in technology. The recommendations are based on the international published literature, and the strength of each recommendation is judged according to the Oxford Centre for Evidence-Based Medicine. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.
To perform a systematic review and meta-analysis of the diagnostic performance of computed tomography (CT) and magnetic resonance (MR) imaging as noninvasive modalities for evaluating hepatocellular ...carcinoma (HCC) in patients with chronic liver disease.
A search of the MEDLINE, EMBASE, and Cochrane Library databases was performed to identify studies providing per-patient or per-lesion diagnostic accuracies of multidetector CT and MR imaging for HCCs in patients with chronic liver disease. Studies published from January 2000 to December 2012 that used a reference standard based on histopathologic findings and/or findings at follow-up were included. Summary estimates of diagnostic accuracy were obtained by using a random-effects model with further exploration with meta-regression and subgroup analyses.
Forty studies (six on multidetector CT, 22 on MR imaging, and 12 on both CT and MR imaging) were included. The studies evaluated a total of 1135 patients with multidetector CT and 2489 patients with MR imaging. The overall per-patient sensitivity of MR imaging was 88% (95% confidence interval CI: 83%, 92%), with a specificity of 94% (95% CI: 85%, 98%). The overall per-lesion sensitivity of MR imaging was higher than that of multidetector CT when the paired data of the 11 available studies were pooled (80% vs 68%, P = .0023). Gadoxetic acid-enhanced MR imaging showed significantly higher per-lesion sensitivity than MR imaging performed with other contrast agents (87% vs 74%, P = .03). Per-lesion sensitivity was significantly lower for HCCs smaller than 1 cm than that for HCCs 1 cm or larger (P < .001 for CT, P = .02 for MR imaging) and for those in explanted livers (P = .04 for CT, P < .001 for MR imaging).
MR imaging showed higher per-lesion sensitivity than multidetector CT and should be the preferred imaging modality for the diagnosis of HCCs in patients with chronic liver disease.
To evaluate the enhancement patterns of intrahepatic mass-forming cholangiocarcinomas (IMCCs) with emphasis on the hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance (MR) ...imaging.
This retrospective study was institutional review board approved, and the requirement for informed consent was waived. Fifty patients (41 men, nine women; mean age, 62.3 years; range, 44-76 years) with IMCC underwent unenhanced and gadoxetic acid-enhanced T1- and T2-weighted MR imaging including dynamic phase and hepatobiliary phase imaging between May 2008 and December 2010. Signal intensity and enhancement patterns of lesions were compared with those of the liver parenchyma in each phase. Conspicuity and margin sharpness of lesions on dynamic phase and HBP images were rated on a 4- or 5-point scale and compared by using the Wilcoxon signed-rank test. Percentage of relative enhancement was compared among pathologic subgroups by using the unpaired Student t test.
On dynamic phase images, 29 of 48 (60%) lesions showed a thin peripheral rim with centripetal or gradual progression. On HBP images, 48 of 50 (96%) IMCCs were hypointense, and two of 50 (4%) were hyperintense. Subjective ratings of conspicuity and margin sharpness were significantly higher on HBP (median scores, 5 and 4, respectively) (P < .001) than on the dynamic phase (median scores, 4 and 3, respectively) images (P < .001). Additional daughter nodules were found in five patients and intrahepatic metastasis was found in one. Percentage of relative enhancement on HBP images was significantly higher in moderately differentiated (66.4% ± 42.1) than in poorly differentiated (36.84% ± 21.5) tumors (P = .039) and in patients without (59.7% ± 28.8) than in those with (24.9% ± 14.7) (P = .036) lymph node metastasis.
The most prevalent enhancement pattern on gadoxetic acid-enhanced MR images of IMCCs was a thin peripheral rim with internal heterogeneous enhancement during the dynamic phase. HBP images showed increased lesion conspicuity and better delineation of daughter nodules and intrahepatic metastasis, which may aid in the diagnosis of IMCC.
The purpose of this study was to investigate the MRI features of gastrointestinal stromal tumors (GISTs) with special emphasis on the dynamic enhancement pattern and findings of diffusion ...restriction.
Forty-two patients with pathologically proven GISTs who underwent MRI that included dynamic contrast-enhanced and diffusion-weighted imaging (DWI) were included in this study. Two abdominal radiologists analyzed the MR images in consensus regarding the morphologic features, enhancement degree and pattern, and findings of diffusion restriction. The mean apparent diffusion coefficient (ADC) values of the tumors were measured by one of the radiologists. The MRI features and mean ADC values were analyzed with respect to tumor size and malignancy risk.
Small GISTs (≤ 5 cm, n = 25) appeared as round tumors with strong and homogeneous arterial enhancement and a persistent enhancement pattern. Large GISTs (> 5 cm, n = 17) appeared as lobulated tumors with mild heterogeneous gradual enhancement, and they frequently exhibited intratumoral cystic change (n = 13). The prevalence of intratumoral cystic change was higher in the moderate to high risk group than in very low to low risk group (p < 0.05). There was negative linear correlation between the mean ADC values and the malignancy risk of GISTs (r = -0.670, p < 0.05).
Small GISTs had MRI features different from the well-known imaging features of large GISTs. The presence of intratumoral cystic change and a low mean ADC value may be helpful for predicting the high malignancy potential of GISTs.
Objectives
To evaluate the diagnostic performance of attenuation imaging (ATI) in the detection of hepatic steatosis compared with a histopathology gold standard.
Methods
We prospectively enrolled ...108 consecutive patients (35 males; median age, 54.0 years) who underwent percutaneous liver biopsy for evaluation of diffuse liver disease between January 2018 and November 2018 in a tertiary academic center. Grayscale ultrasound examination with ATI was performed just before biopsy, and an attenuation coefficient (AC) was obtained from each patient. The degree of hepatic steatosis, fibrosis stage, and necroinflammatory activity were assessed on histopathologic examination. The significant factor associated with the AC was found by a linear regression analysis, and the diagnostic performance of the AC for the classification into each hepatic steatosis stage was evaluated by receiver operating characteristic (ROC) analysis.
Results
The distribution of hepatic steatosis grade on histopathology was 53/11/22/16/6 for none/mild (< 10%)/mild (≥ 10%)/moderate/severe steatosis, respectively. The area under the ROC curve, sensitivity, specificity, and optimal cutoff AC value for detection of hepatic steatosis ranged from 0.843–0.926, 74.5–100.0%, 77.4–82.8%, and 0.635–0.745, respectively. Multivariate analysis revealed that the degree of steatosis was the only significant determinant factor for the AC.
Conclusions
The AC from ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis. The degree of steatosis was the only significant factor affecting the AC, whereas fibrosis and inflammation were not.
Key Points
• Attenuation imaging (ATI) is based on two-dimensional grayscale ultrasound images that can incorporate into routine ultrasound examinations with less than 2 min of acquisition time.
• ATI provided good diagnostic performance in detecting the varying degrees of hepatic steatosis with an area under the ROC curves ranging from 0.843 to 0.926, and there was no technical failure in this study indicating high applicability of this technique.
• The degree of hepatic steatosis was the only significant factor affecting the result of ATI examination.
Purpose
To investigate staging accuracy of multidetector CT (MDCT) for pancreatic neuroendocrine tumour (PNET) and diagnostic performance for differentiation of PNET from pancreatic adenocarcinoma.
...Material and methods
We included 109 patients with surgically proven PNET (NETG1 = 66, NETG2 = 31, NEC = 12) who underwent MDCT. Two reviewers assessed stage and presence of predefined CT findings. We analysed the relationship between CT findings and tumour grade. Using PNETs with uncommon findings, we also estimated the possibility of PNET or adenocarcinoma.
Results
Accuracy for T stage was 85–88 % and N-metastasis was 83–89 %. Common findings included well circumscribed, homogeneously enhanced, hypervascular mass, common in lower grade tumours (
p
< 0.05). Uncommon findings included ill-defined, heterogeneously enhanced, hypovascular mass and duct dilation, common in higher grade tumours (
p
< 0.05). Using 31 PNETs with uncommon findings, diagnostic performance for differentiation from adenocarcinoma was 0.760–0.806. Duct dilatation was an independent predictor for adenocarcinoma (Exp(B) = 4.569). PNETs with uncommon findings were associated with significantly worse survival versus PNET with common findings (62.7 vs. 95.7 months,
p
< 0.001).
Conclusion
MDCT is useful for preoperative evaluation of PNET; it not only accurately depicts the tumour stage but also prediction of tumour grade, because uncommon findings were more common in higher grade tumours.
Key Points
•
CT accurately depicts the T stage and node metastasis of PNET.
•
Uncommon findings were more common in higher grade tumours.
•
CT information may be beneficial for optimal therapeutic planning.
To evaluate the diagnostic potential of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM)-derived parameters for differentiation of common pancreatic tumors, chronic ...pancreatitis, and normal pancreas and for characterization of the malignancy potential of intraductal papillary mucinous neoplasms (IPMNs).
The institutional review board approved this retrospective study, and informed consent was waived. Ninety-three consecutive patients with surgically resected and pathologically confirmed pancreatic tumors (39 pancreatic adenocarcinomas PACs, 17 neuroendocrine tumors NETs, and 37 IPMNs), seven patients with chronic pancreatitis, and 26 patients with a normal pancreas were included in this study. All patients underwent pancreatic 3.0-T magnetic resonance imaging, including IVIM diffusion-weighted imaging with 10 b values used (from 0 to 1000 sec/mm(2)). The ADC, slow component of diffusion (D(slow)), incoherent microcirculation (D(fast)), and perfusion fraction (f) were calculated. Steel-Dwass and Mann-Whitney U tests were used for comparison. The diagnostic performance of the parameters was evaluated by using receiver operating characteristic (ROC) analysis with Bonferroni correction.
Among ADC- and IVIM-derived parameters, D(fast) and f values of PACs were significantly lower than those of normal pancreas, chronic pancreatitis, and NETs (all P < .05 in post hoc analyses). For differentiation of PACs from NETs, f and D(fast) showed a significant difference (P < .0001 for both) and were more useful parameters than ADC and D(slow) in ROC analysis (all P < .05). Malignant IPMNs had significantly lower ADC and D(slow) values and higher D(fast) and f values when compared with benign IPMNs (all P < .05). In ROC analysis, f showed the highest area under the ROC curve value for distinguishing malignant from benign IPMNs.
IVIM-derived perfusion-related parameters could be helpful for the differentiation of common malignant tumors in the pancreas and for distinguishing malignant from benign IPMNs. D(fast) and f were more valuable parameters in the differentiation of PACs from NETs than were ADC and D(slow).
Objectives
To determine whether multislice T1 mapping of the liver using a modified look-locker inversion recovery (MOLLI) sequence on gadoxetic acid-enhanced magnetic resonance imaging (MRI) can be ...used as a quantitative tool to estimate liver function and predict the presence of oesophageal or gastric varices.
Methods
Phantoms filled with gadoxetic acid were scanned three times using MOLLI sequence to test repeatability. Patients with chronic liver disease or liver cirrhosis who underwent gadoxetic acid-enhanced liver MRI including MOLLI sequence at 3 T were included (
n
= 343). Pre- and postcontrast T1 relaxation times of the liver (T1liver), changes between pre- and postcontrast T1liver (ΔT1liver), and adjusted postcontrast T1liver (postcontrast T1liver-T1spleen/T1spleen) were compared among Child-Pugh classes. In 62 patients who underwent endoscopy, all T1 parameters and spleen sizes were correlated with varices.
Results
Phantom study showed excellent repeatability of MOLLI sequence. As Child-Pugh scores increased, pre- and postcontrast T1liver were significantly prolonged (
P
< 0.001), and ΔT1liver and adjusted postcontrast T1liver decreased (
P
< 0.001). Adjusted postcontrast T1liver and spleen size were independently associated with varices (
R
2
= 0.29,
P
< 0.001).
Conclusions
T1 mapping of the liver using MOLLI sequence on gadoxetic acid-enhanced MRI demonstrated potential in quantitatively estimating liver function, and adjusted postcontrast T1liver was significantly associated with varices.
Key Points
• T1 mapping using MOLLI sequence can be achieved within a breath-hold.
• T1liver measured by MOLLI sequence provided excellent short-term repeatability.
• Precontrast and postcontrast T1liver were significantly prolonged as Child-Pugh scores increased.
• Adjusted postcontrast T1liver and spleen size were independently associated with varices.
The purpose of this study was to determine the optimal minimum number of liver stiffness measurements on shear wave elastography (SWE) and to evaluate the frequency of technical failures and ...unreliable stiffness measurements and the intraobserver reproducibility of SWE.
This retrospective study was approved by our Institutional Review Board, and informed consent was waived. From August 2011 to January 2013, 540 patients underwent abdominal sonography, including SWE. In 86 patients (group 1), the minimum number of examinations was determined by comparing the intraclass correlation coefficient (ICC) of subsets of the first 2 to 14 measurements with that from 15 measurements. In 454 patients (group 2), 2 SWE sessions were performed in the right lobe within 1 day. Technical failure was defined as when no or little signal was obtained in the elastogram during the first 5 acquisitions; unreliable SWE results were defined as when the interquartile range/median liver stiffness value exceeded 30%. Intraobserver reproducibility was assessed using ICCs and Bland-Altman plots.
In group 1, the ICCs did not significantly increase after the first 6 measurements. In group 2, there were technical failures and unreliable results in 47 patients (10.35%) and 74 patients (16.29%), respectively. In 407 patients, after excluding technical failures, there was no significant difference in the median liver stiffness values between the 2 sessions (6.95 versus 6.86 kPa; P > .05). The overall intraobserver reproducibility was excellent (ICC, 0.95).
In this study, the optimal minimum number of SWE measurements was 6, and SWE using 6 measurements showed excellent intraobserver reproducibility.
PDF
