Search

Objective To accurately estimate liver PDFF from chemical shift-encoded (CSE) MRI using a deep learning (DL)-based Multi-Decoder Water-Fat separation Network (MDWF-Net), that operates over complex-valued CSE-MR images with only 3 echoes. Methods The proposed MDWF-Net and a U-Net model were independently trained using the first 3 echoes of MRI data from 134 subjects, acquired with conventional 6-echoes abdomen protocol at 1.5 T. Resulting models were then evaluated using unseen CSE-MR images obtained from 14 subjects that were acquired with a 3-echoes CSE-MR pulse sequence with a shorter duration compared to the standard protocol. Resulting PDFF maps were qualitatively assessed by two radiologists, and quantitatively assessed at two corresponding liver ROIs, using Bland Altman and regression analysis for mean values, and ANOVA testing for standard deviation (STD) (significance level: .05). A 6-echo graph cut was considered ground truth. Results Assessment of radiologists demonstrated that, unlike U-Net, MDWF-Net had a similar quality to the ground truth, despite it considered half of the information. Regarding PDFF mean values at ROIs, MDWF-Net showed a better agreement with ground truth (regression slope = 0.94, R2 = 0.97) than U-Net (regression slope = 0.86, R2 = 0.93). Moreover, ANOVA post hoc analysis of STDs showed a statistical difference between graph cuts and U-Net (p p = .53). Conclusion MDWF-Net showed a liver PDFF accuracy comparable to the reference graph cut method, using only 3 echoes and thus allowing a reduction in the acquisition times. Clinical relevance statement We have prospectively validated that the use of a multi-decoder convolutional neural network to estimate liver proton density fat fraction allows a significant reduction in MR scan time by reducing the number of echoes required by 50%. Key Points • Novel water-fat separation neural network allows for liver PDFF estimation by using multi-echo MR images with a reduced number of echoes. • Prospective single-center validation demonstrated that echo reduction leads to a significant shortening of the scan time, compared to standard 6-echo acquisition. • Qualitative and quantitative performance of the proposed method showed no significant differences in PDFF estimation with respect to the reference technique.

Radiotherapy (RT) is an essential part of breast cancer (BC) treatments. Unfortunately, heart exposure to radiation can also impair the long-term survival of patients. Our study aimed to quantify the oncological benefit and the cardiovascular (CV) risk associated with modern RT in a real-world cohort of BC patients. Our descriptive study enrolled BC patients who received adjuvant RT. Ten-year overall survival (OS) was estimated using Predict® version 2.1 (National Health Service, London, UK). The basal risk of CV events was estimated using the American Heart Association (ACC/AHA) CV score. Treatment volumes and mean cardiac doses were obtained from RT treatment plan records. The increased risk of CV events due to RT was estimated using a model proposed by Darby. The risk of acute myocardial infarction or stroke mortality was estimated using HeartScore® (European Society of Cardiology, Brussels, Belgium). A total of 256 BC patients were included in the study. The average age of patients was 57 years old (range: 25–91); 49.6% had left BC. The mean cardiac dose was 166 cGy (interquartile range (IQR) 94–273); the estimated hazard ratio (HR) for CV disease was HR 1.12 (confidence interval (CI) 1.04–1.24). The estimated baseline 10-year CV risk was 5.6% (0.2 to 51.2); CV risk increased by 0.9% (range 0.02–35.47%) after RT. The absolute risk of 10-year mortality from CV disease was 2.5% (0.1–9); RT was associated with an estimated 4.9% survival benefit (3.73–6.07) against BC death and a 0.23% (0.17–0.29) estimated increase in CV mortality. Modern RT decreased 10-year BC mortality by 4% but increased CV mortality by 0.2% in this cohort. Our findings encourage the implementation of personalized adjuvant RT treatments that balance risks and benefits to improve long-term BC patient survival.

Several deep learning architectures have been proposed over the last years to deal with the task of generating a written report given an imaging exam as input. Most works evaluate the generated reports using standard Natural Language Processing (NLP) metrics (e.g. BLEU, ROUGE), reporting significant progress. This article contrast this progress by comparing state of the art (SOTA) models against weak baselines. We show that simple and even naive approaches yield near SOTA performance on most traditional NLP metrics. We conclude that evaluation methods in this task should be further studied towards correctly measuring clinical accuracy, involving physicians to contribute to this end.

Every year physicians face an increasing demand of image-based diagnosis from patients, a problem that can be addressed with recent artificial intelligence methods. In this context, we survey works in the area of automatic report generation from medical images, with emphasis on methods using deep neural networks, with respect to: (1) Datasets, (2) Architecture Design, (3) Explainability and (4) Evaluation Metrics. Our survey identifies interesting developments, but also remaining challenges. Among them, the current evaluation of generated reports is especially weak, since it mostly relies on traditional Natural Language Processing (NLP) metrics, which do not accurately capture medical correctness., Accepted for publication in ACM CSUR

Purpose: To assess intra-observer, inter-observer and inter-modality (CT vs. MRI) reproducibility of liver surface nodularity (LSN) scores measured with software used for detection of liver fibrosis. Methods: This IRB-approved retrospective study included patients with both abdominal CT and MRI within 6 months of histopathologic sampling. Two independent observers used post-processing software to quantify LSN scores on axial non-contrast CT (NCT), axial contrast-enhanced CT (CECT), axial T2-weighted (T2W) HASTE, and axial and coronal post-gadoxetic acid T1-weighted (T1W) images obtained during the hepatobiliary phase (HBP). Ten slices were used to acquire the LSN scores. Intra-observer, inter-observer, and inter-modality (CT vs. MRI) reproducibility were assessed with intraclass correlation coefficient (ICC) and coefficients of variability (CV). Accuracy for detection of cirrhosis was evaluated for each technique. Results: 26 patients (M/F 19/7, mean age 57 years), including 7 with cirrhosis (26.9%), were assessed. Technical failure occurred with NCT (1/23, 4.3%) and T2 HASTE (8/28, 28.6%). Intra-observer reproducibility was excellent for NCT, CECT, axial and coronal T1W HBP [ICC â¥Â 0.92, CV â¤Â 8%]. Inter-observer reproducibility was also excellent for NCT and CECT (ICC â¥Â 0.95, CV â¤Â 7.3%) and for coronal T1W HBP (ICC = 0.84, CV = 5.6%). There was fair to moderate agreement between CT and MRI (ICC 0.20â0.44). There were significant differences in mean LSN scores between non-cirrhotic and cirrhotic patients with NCT (2.6 vs. 4.2, p = 0.04) and T1W HBP (3.7 vs. 4.6; p = 0.01) images, with AUCs of 0.81 and 0.82, respectively. Conclusions: LSN measurement is highly reproducible with NCT and post-contrast T1W HBP on MRI, with different results obtained between CT and MRI. Keywords: Liver surface nodularity, Fibrosis, Cirrhosis, CT, MRI

To assess the value of qualitative and quantitative MRI radiomics features for noninvasive prediction of immuno-oncologic characteristics and outcomes of hepatocellular carcinoma (HCC).This retrospective, IRB-approved study included 48 patients with HCC (M/F 35/13, mean age 60y) who underwent hepatic resection or transplant within 4 months of abdominal MRI. Qualitative imaging traits, quantitative nontexture related and texture features were assessed in index lesions on contrast-enhanced T1-weighted and diffusion-weighted images. The association of imaging features with immunoprofiling and genomics features was assessed using binary logistic regression and correlation analyses. Binary logistic regression analysis was also employed to analyse the association of radiomics, histopathologic and genomics features with radiological early recurrence of HCC at 12 months.Qualitative (r = - 0.41-0.40, p 0.042) and quantitative (r = - 0.52-0.45, p 0.049) radiomics features correlated with immunohistochemical cell type markers for T-cells (CD3), macrophages (CD68) and endothelial cells (CD31). Radiomics features also correlated with expression of immunotherapy targets PD-L1 at protein level (r = 0.41-0.47, p 0.029) as well as PD1 and CTLA4 at mRNA expression level (r = - 0.48-0.47, p 0.037). Finally, radiomics features, including tumour size, showed significant diagnostic performance for assessment of early HCC recurrence (AUC 0.76-0.80, p 0.043), while immunoprofiling and genomic features did not (p = 0.098-0929).MRI radiomics features may serve as noninvasive predictors of HCC immuno-oncological characteristics and tumour recurrence and may aid in treatment stratification of HCC patients. These results need prospective validation.• MRI radiomics features showed significant associations with immunophenotyping and genomics characteristics of hepatocellular carcinoma. • Radiomics features, including tumour size, showed significant associations with early hepatocellular carcinoma recurrence after resection.

This multicenter study evaluated the effect of variations in arterial input function (AIF) determination on pharmacokinetic (PK) analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data using the shutter-speed model (SSM). Data acquired from eleven prostate cancer patients were shared among nine centers. Each center used a site-specific method to measure the individual AIF from each data set and submitted the results to the managing center. These AIFs, their reference tissue-adjusted variants, and a literature population-averaged AIF, were used by the managing center to perform SSM PK analysis to estimate Ktrans (volume transfer rate constant), ve (extravascular, extracellular volume fraction), kep (efflux rate constant), and τi (mean intracellular water lifetime). All other variables, including the definition of the tumor region of interest and precontrast T1 values, were kept the same to evaluate parameter variations caused by variations in only the AIF. Considerable PK parameter variations were observed with within-subject coefficient of variation (wCV) values of 0.58, 0.27, 0.42, and 0.24 for Ktrans, ve, kep, and τi, respectively, using the unadjusted AIFs. Use of the reference tissue-adjusted AIFs reduced variations in Ktrans and ve (wCV = 0.50 and 0.10, respectively), but had smaller effects on kep and τi (wCV = 0.39 and 0.22, respectively). kep is less sensitive to AIF variation than Ktrans, suggesting it may be a more robust imaging biomarker of prostate microvasculature. With low sensitivity to AIF uncertainty, the SSM-unique τi parameter may have advantages over the conventional PK parameters in a longitudinal study.

Purpose To assess the correlation between intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) metrics in hepatocellular carcinoma (HCC) and liver parenchyma. Materials and Methods Twenty-five patients with HCC (M/F 23/2, mean age 58 years) underwent abdominal MRI at 1.5 or 3.0T, including IVIM-DWI (with 16 b-values) and DCE-MRI (3D FLASH sequence, mean temporal resolution of 2.3 sec). IVIM-DWI parameters (pseudodiffusion coefficient, D*, diffusion coefficient, D, and perfusion fraction, PF) were quantified in HCC lesions and liver parenchyma using a Bayesian fitting algorithm. DCE-MRI parameters (arterial flow, Fa, portal flow, Fp, total flow, Ft, mean transit time, MTT, distribution volume, DV, and arterial fraction, ART) were quantified using a dual-input single-compartment model. Correlations between IVIM-DWI and DCE-MRI parameters were assessed using a Spearman correlation test. Results Thirty-three HCC lesions (average size 5.0 ± 3.6 cm) were analyzed. D, D*, and PF were all significantly lower in HCC vs. liver (P

Purpose. To compare multiparametric (mp)FDG-PET/MRI metrics between hepatocellular carcinoma (HCC) and liver parenchyma and to assess the correlation between mpMRI and FDG-PET standard uptake values (SUVs) in liver parenchyma and HCC. Methods. This prospective, institutional review board-approved study enrolled 15 patients (M/F 12/3; mean age 61 y) with HCC. mpMRI including blood-oxygen-level-dependent (BOLD) MRI, intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), and dynamic contrast-enhanced-(DCE-) MRI was performed simultaneously with 18F-FDG-PET on a 3T PET/MRI hybrid system. Quantitative BOLD, IVIM and DCE-MRI parameters (Tofts model (TM) and shutter-speed model (SSM)), and PET parameters (SUVmean and SUVmax) were quantified and compared between HCC lesions and liver parenchyma using Wilcoxon signed-rank tests. SUV ratios between HCCs and liver were also calculated (SUVmean T/L and SUVmax T/L). Diagnostic performance of (combined) mp-PET/MRI parameters for characterization of HCC was assessed using ROC analysis. Spearman correlations between PET and mpMRI parameters in HCC tumors and liver parenchyma were evaluated. Results. 21 HCC lesions (mean size 4.0 ± 2.4 cm; range 2–13 cm) were analyzed. HCCs exhibited significantly higher arterial fraction (from DCE-MRI) and lower R2∗ pre-O2 and post-O2 (from BOLD-MRI) versus liver parenchyma (P<0.032). The highest diagnostic performance for differentiation between HCC and liver parenchyma was achieved for combined ART SSM and R2∗ post-O2 (AUC = 0.91). SUVmax showed reasonable performance for differentiation of HCC versus liver (AUC = 0.75). In HCC, DCE-MRI parameters Ktrans (TM and SSM) and ve TM exhibited significant negative correlations with SUVmax T/L (r ranges from −0.624 to −0.566; FDR-adjusted P<0.050). Conclusions. Despite the observed reasonable diagnostic performance of FDG-PET SUVmax for HCC detection and several significant correlations between FDG-PET SUV and DCE-MRI parameters, FDG-PET did not provide clear additional value for HCC characterization compared to mpMRI in this pilot study.

Purpose To assess interplatform reproducibility of liver stiffness (LS) and spleen stiffness (SS) measured with magnetic resonance elastography (MRE) based on a 2D gradient echo (GRE) sequence. Materials and Methods This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved study involved 12 subjects (five healthy volunteers and seven patients with liver disease). A multislice 2D-GRE-based MRE sequence was performed using two systems from different vendors (3.0T GE and 1.5T Siemens) on the same day. Two independent observers measured LS and SS on confidence maps. Bland–Altman analysis (with coefficient of reproducibility, CR), coefficient of variability (CV), and intraclass correlation (ICC) were used to analyze interplatform, intra- and interobserver variability. Human data were validated using a gelatin-based phantom. Results There was excellent reproducibility of phantom stiffness measurement (CV 4.4%). Mean LS values were 3.44–3.48 kPa and 3.62–3.63 kPa, and mean SS values were 7.54–7.91 kPa and 8.40–8.85 kPa at 3.0T and 1.5T for observers 1 and 2, respectively. The mean CVs between platforms were 9.2%–11.5% and 13.1%–14.4% for LS and SS, respectively, for observers 1 and 2. There was excellent interplatform reproducibility (ICC >0.88 and CR 0.99, CV 0.97, CV and CR

Purpose To quantify baseline relaxation rates R2* and R1 in the abdomen, their changes after respiratory challenges, and their reproducibility in healthy volunteers and patients with hepatocellular carcinoma (HCC) at 1.5T and 3.0T. Materials and Methods R2* measurements were acquired in the liver in 8 volunteers and 27 patients with 34 HCCs using multiecho T2* at baseline and after respiratory challenges with 100% oxygen (O2) and carbogen (CB = 95%O2/5%CO2). R1 was measured at 1.5T in one volunteer and 21 patients with 23 HCCs. Test–retest coefficient of variation (CV) was assessed in 10 subjects. Intra- and interobserver variability of R2* and R1 measurements was assessed in 12 and 10 patients, respectively. Parameters for HCC, liver, and muscle were compared between baseline and after gas challenges. Results We observed that R2* and R1 imaging of HCCs with O2 and CB is feasible and reproducible (test–retest CV R2* 0.88/R1>0.7 and CV R2*

To develop a highly accelerated phase-contrast cardiac-gated volume flow measurement (four-dimensional [4D] flow) magnetic resonance (MR) imaging technique based on spiral sampling and dynamic compressed sensing and to compare this technique with established phase-contrast imaging techniques for the quantification of blood flow in abdominal vessels.This single-center prospective study was compliant with HIPAA and approved by the institutional review board. Ten subjects (nine men, one woman; mean age, 51 years; age range, 30-70 years) were enrolled. Seven patients had liver disease. Written informed consent was obtained from all participants. Two 4D flow acquisitions were performed in each subject, one with use of Cartesian sampling with respiratory tracking and the other with use of spiral sampling and a breath hold. Cartesian two-dimensional (2D) cine phase-contrast images were also acquired in the portal vein. Two observers independently assessed vessel conspicuity on phase-contrast three-dimensional angiograms. Quantitative flow parameters were measured by two independent observers in major abdominal vessels. Intertechnique concordance was quantified by using Bland-Altman and logistic regression analyses.There was moderate to substantial agreement in vessel conspicuity between 4D flow acquisitions in arteries and veins (κ = 0.71 and 0.61, respectively, for observer 1; κ = 0.71 and 0.44 for observer 2), whereas more artifacts were observed with spiral 4D flow (κ = 0.30 and 0.20). Quantitative measurements in abdominal vessels showed good equivalence between spiral and Cartesian 4D flow techniques (lower bound of the 95% confidence interval: 63%, 77%, 60%, and 64% for flow, area, average velocity, and peak velocity, respectively). For portal venous flow, spiral 4D flow was in better agreement with 2D cine phase-contrast flow (95% limits of agreement: -8.8 and 9.3 mL/sec, respectively) than was Cartesian 4D flow (95% limits of agreement: -10.6 and 14.6 mL/sec).The combination of highly efficient spiral sampling with dynamic compressed sensing results in major acceleration for 4D flow MR imaging, which allows comprehensive assessment of abdominal vessel hemodynamics in a single breath hold.

OBJECTIVE. The objective of our study was to evaluate the performance of a high-spatial-resolution 2D phase-contrast (PC) MRI technique accelerated with compressed sensing for portal vein (PV) and hepatic artery (HA) flow quantification in comparison with a standard PC MRI sequence. SUBJECTS AND METHODS. In this prospective study, two PC MRI sequences were compared, one with parallel imaging acceleration and low spatial resolution (generalized autocalibrating partial parallel acquisition [GRAPPA]) and one with compressed sensing acceleration and high spatial resolution (sparse). Seventy-six patients were assessed, including 37 patients with cirrhosis. Two observers evaluated PC image quality. Quantitative analyses yielded a mean velocity, flow, and vessel area for the PV and HA and an arterial fraction. The PC techniques were compared using the paired Wilcoxon test and Bland-Altman statistics. The sensitivity of the flow parameters to the severity of cirrhosis was also assessed. RESULTS. Vessel delineation was significantly improved using the PC sparse sequence (p < 0.034). For both in vitro and in vivo measurements, PC sparse yielded lower estimates for vessel area and flow, and larger differences between PC GRAPPA and PC sparse were observed in the HA. PV velocity and flow were significantly lower in patients with cirrhosis on both PC sparse (p < 0.001 and p = 0.042, respectively) and PC GRAPPA (p < 0.001 and p = 0.005, respectively). PV velocity correlated negatively with Child-Pugh class (r = -0.50, p < 0.001), whereas the arterial fraction measured with PC sparse was higher in patients with Child-Pugh class B or C disease than in those with Child-Pugh class A disease, with a trend toward significance (p = 0.055). CONCLUSION. A high-spatial-resolution highly accelerated compressed sensing technique (PC sparse) allows total hepatic blood flow measurements obtained in 1 breath-hold, provides improved delineation of the hepatic vessels compared with a standard PC MRI sequence (GRAPPA), and can potentially be used for the noninvasive assessment of liver cirrhosis.

Purpose To compare intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) of the liver between 1.5T and 3.0T in terms of parameter quantification and inter-platform reproducibility. Materials and methods In this IRB approved prospective study, 19 subjects (17 patients with chronic liver disease and 2 healthy volunteers) underwent two repeat scans at 1.5T and 3.0T. Each scan included IVIM DWI using 16 b values from 0 to 800s/mm 2 . A single observer measured IVIM parameters for each platform and estimated signal to noise ratio (eSNR) at b 0, 200, 400 and 800s/mm 2 . Wilcoxon paired tests were used to compare liver eSNR and IVIM parameters. Inter-platform reproducibility was assessed by calculating within-subject coefficient of variation (CV) and Bland–Altman limits of agreement. An ice water phantom was used to test ADC variability between the two MRI systems. Results The mean invitro difference in ADC between the two platforms was 6.8%. eSNR was significantly higher at 3.0T for all selected b values ( p =0.006–0.020), except for b 0 ( p =0.239). Liver IVIM parameters were significantly different between 1.5T and 3.0T ( p =0.005–0.044), except for ADC ( p =0.748). The inter-platform reproducibility of true diffusion coefficient ( D ) and ADC were good, with mean CV of 10.9% and 11.1%, respectively. Perfusion fraction (PF) and pseudodiffusion coefficient ( D *) showed more limited inter-platform reproducibility (mean CV of 22.6% for PF and 46.9% for D *). Conclusion Liver D and ADC values showed good reproducibility between 1.5T and 3.0T platforms; while there was more variability in PF, and large variability in D * parameters between the two platforms. These findings may have implications for drug trials assessing the role of IVIM DWI in tumor response and liver fibrosis.

Background and AimsRecently, smooth muscle hypertrophy has been suggested to be a contributor to small bowel lesions secondary to Crohn’s disease [CD], in addition to inflammation and fibrosis. Here, we assess the value of magnetic resonance imaging [MRI] for the characterisation of histopathological tissue composition of small bowel CD, including inflammation, fibrosis, and smooth muscle hypertrophy.MethodsA total of 35 consecutive patients [male/female 17/18, mean age 33 years] with ileal CD, who underwent small bowel resection and a preoperative contrast-enhanced MRI examination within 1 month before surgery, were retrospectively included. Image assessment included qualitative [pattern/degree of enhancement, presence of ulcerations/fistulas/abscesses] and quantitative parameters [wall thickness on T2/T1-weighted images [WI], enhancement ratios, apparent diffusion coefficient [ADC], Clermont and Magnetic Resonance Index of Activity [MaRIA] scores). MRI parameters were compared with histopathological findings including active inflammation, collagen deposition, and muscle hypertrophy using chi square/Fisher or Mann-Whitney tests and univariate/multivariate logistic/linear regression analyses.ResultsForty ileal segments were analysed in 35 patients. Layered pattern at early-post-contrast phase was more prevalent (odds ratio [OR] = 8; p = 0.008), ADC was significantly lower [OR = 0.005; p = 0.022], and MaRIA score was significantly higher [OR = 1.125; p = 0.022] in inflammation grades 2–3 compared with grade 1. Wall thickness on T2WI was significantly increased [OR = 1.688; p = 0.043], and fistulas [OR = 14.5; p = 0.017] were more prevalent in segments with disproportionately increased muscle hypertrophy versus those with disproportionately increased fibrosis. MaRIA/Clermont scores, wall thickness on T1WI and T2WI, and ADC were all significantly correlated with degree of muscular hypertrophy.ConclusionsMRI predicts the degree of inflammation, and can distinguish prominent muscle hypertrophy from prominent fibrosis in ileal CD with reasonable accuracy (area under receiver operating characteristic curve [AUROC] > 0.7).

The aim of the study was to correlate tumor stiffness (TS) measured with MR elastography (MRE) with degree of tumor enhancement and necrosis on contrast-enhanced T1-weighted imaging (CE-T1WI) in hepatocellular carcinomas (HCC) treated with Yttrium-90 radioembolization (RE) or transarterial chemoembolization plus radiofrequency ablation (TACE/RFA). This retrospective study was IRB-approved and the requirement for informed consent was waived. 52 patients (M/F 38/14, mean age 67 years) with HCC who underwent RE (n = 22) or TACE/RFA (n = 30) and 11 controls (M/F 6/5, mean age 64 years) with newly diagnosed untreated HCC were included. The MRI protocol included a 2D MRE sequence. TS and LS (liver stiffness) were measured on stiffness maps. Degree of tumor necrosis was assessed on subtraction images by two observers, and tumor enhancement ratios (ER) were calculated on CE-T1WI by one observer. 63 HCCs (mean size 3.2 ± 1.6 cm) were evaluated. TS was significantly lower in treated vs. untreated tumors (3.9 ± 1.8 vs. 6.9 ± 3.4 kPa, p = 0.006) and also compared to LS (5.3 ± 2.2 kPa, p = 0.002). There were significant correlations between TS and each of enhancement ratios (r = 0.514, p = 0.0001), and percentage of necrosis (r = −0.540, p = 0.0001). The observed correlations were stronger in patients treated with RE (TS vs. ER, r = 0.636, TS vs. necrosis, r = −0.711, both p = 0.0001). Percentage of necrosis and T1-signal in native T1WI were significant independent predictors of TS (p = 0.0001 and 0.001, respectively). TS measured with MRE shows a significant correlation with tumor enhancement and necrosis, especially in HCCs treated with RE.

Purpose: The purpose of this study was to evaluate the diagnostic performance of a “simulated” abbreviated MRI (AMRI) protocol using diffusion-weighted imaging (DWI) and T1-weighted (T1w) imaging obtained at the hepatobiliary phase (HBP) post gadoxetic acid injection alone and in combination, compared to dynamic contrast-enhanced (CE)-T1w imaging for the detection of hepatocellular carcinoma (HCC). Methods: This was an IRB approved HIPAA compliant retrospective single institution study including patients with liver disease who underwent gadoxetic acid-enhanced MRI for HCC diagnosis. Three independent observers assessed 2 sets of images (full CE-set and AMRI including DWI+T1w-HBP). Diagnostic performance of T1w-HBP and DWI alone and in combination was compared to that of CE-set. All imaging sets included unenhanced T1w and T2w sequences. A preliminary analysis was performed to assess cost savings of AMRI protocol compared to a full MRI study. Results: 174 patients including 62 with 80 HCCs were assessed. Equivalent per-patient sensitivity and negative predictive value (NPV) were observed for DWI (85.5% and 92.2%, pooled data) and T1w-HBP (89.8% and 94.2%) (P = 0.1–0.7), while these were significantly lower for the full AMRI protocol (DWI+T1w-HBP, 80.6% and 80%, P = 0.02) when compared to CE-set (90.3% and 94.9%). Higher specificity and positive predictive value were observed for CE-set vs. AMRI (P = 0.02). The estimated cost reduction of AMRI versus full MRI ranged between 30.7 and 49.0%. Conclusion: AMRI using DWI and T1w-HBP has a clinically acceptable sensitivity and NPV for HCC detection. This could serve as the basis for a future study assessing AMRI for HCC screening and surveillance. © 2016, Springer Science+Business Media New York.

Tumour heterogeneity poses a significant challenge for treatment stratification. The goals of this study were to quantify heterogeneity in hepatocellular carcinoma (HCC) using multiparametric magnetic resonance imaging (mpMRI), and to report preliminary data correlating quantitative MRI parameters with advanced histopathology and gene expression in a patient subset. Thirty-two HCC patients with 39 HCC lesions underwent mpMRI including diffusion-weighted imaging (DWI), blood-oxygenation-level-dependent (BOLD), tissue-oxygenation-level-dependent (TOLD) and dynamic contrast-enhanced (DCE)-MRI. Histogram characteristics [central tendency (mean, median) and heterogeneity (standard deviation, kurtosis, skewness) MRI parameters] in HCC and liver parenchyma were compared using Wilcoxon signed-rank tests. Histogram data was correlated between MRI methods in all patients and with histopathology and gene expression in 14 patients. HCCs exhibited significantly higher intra-tissue heterogeneity vs. liver with all MRI methods (P GLUL, pharmacological target FGFR4, stemness markers EPCAM and KRT19 and immune checkpoint PDCD1. Histogram analysis combining central tendency and heterogeneity mpMRI features is promising for non-invasive HCC characterization on the imaging, histologic and genomics levels.

To compare MR elastography (MRE) using a single and a dual driver excitation for the quantification of hepatic and splenic stiffness (HS and SS), and to investigate the performance of HS and SS measured with single or dual driver excitation for the detection of liver cirrhosis in subjects with liver disease.This prospective HIPAA compliant and IRB approved study involved 49 subjects who underwent MRE at 3.0T, comparing three different acquisition methods (single driver on the liver, single driver on the spleen and dual driver acoustic excitation). A Mann-Whitney test was used to assess changes in stiffness values. Bland-Altman analysis was used to compare single and dual driver configurations for each organ. Performance for detection of liver cirrhosis was assessed using ROC analysis. Pearson correlation was used to estimate the dependence of HS and SS on spleen size.There were 40 noncirrhotic and 9 cirrhotic patients. There was good agreement between stiffness values measured with a single or a dual driver (Bland-Altman limits of agreement -14.3 % to 18.9 % and -18.1 % to 29.7 %, CV 6.4 % and 9.4 %, for HS and SS. respectively). HS and SS were higher in subjects with liver cirrhosis (p0.001), with excellent detection performance (AUROC range 0.87-0.93). SS correlated strongly with spleen size (r = 0.69, p0.001), while HS showed weak correlation (r = 0.38, p = 0.006).Using a dual acoustic driver configuration, hepatic and splenic stiffness can be simultaneously estimated with good concordance with single driver measurement.

OBJECTIVE The aim of this study was to compare 2-dimensional (2D) gradient recalled echo (GRE) and 2D spin echo echoplanar imaging (SE-EPI) magnetic resonance elastography (MRE) sequences of the liver in terms of image quality and quantitative liver stiffness (LS) measurement. MATERIALS AND METHODS This prospective study involved 50 consecutive subjects (male/female, 33/17; mean age, 58 years) who underwent liver magnetic resonance imaging at 3.0 T including 2 MRE sequences, 2D GRE, and 2D SE-EPI (acquisition time 56 vs 16 seconds, respectively). Image quality scores were assessed by 2 independent observers based on wave propagation and organ coverage on the confidence map (range, 0-15). A third observer measured LS on stiffness maps (in kilopascal). Mean LS values, regions of interest size (based on confidence map), and image quality scores between SE-EPI and GRE-MRE were compared using paired nonparametric Wilcoxon test. Reproducibility of LS values between the 2 sequences was assessed using intraclass coefficient correlation, coefficient of variation, and Bland-Altman limits of agreement. T2* effect on image quality was assessed using partial Spearman correlation. RESULTS There were 4 cases of failure with GRE-MRE and none with SE-EPI-MRE. Image quality scores and region of interest size were significantly higher using SE-EPI-MRE versus GRE-MRE (P < 0.0001 for both measurements and observers). Liver stiffness measurements were not significantly different between the 2 sequences (3.75 ± 1.87 kPa vs 3.55 ± 1.51 kPa, P = 0.062), were significantly correlated (intraclass coefficient correlation, 0.909), and had excellent reproducibility (coefficient of variation, 10.2%; bias, 0.023; Bland-Altman limits of agreement, -1.19; 1.66 kPa). Image quality scores using GRE-MRE were significantly correlated with T2* while there was no correlation for SE-EPI-MRE. CONCLUSIONS Our data suggest that SE-EPI-MRE may be a better alternative to GRE-MRE. The diagnostic performance of SE-EPI-MRE for detection of liver fibrosis needs to be assessed in a future study.

Dynamic contrast-enhanced MRI (DCE-MRI) has been widely used in tumor detection and therapy response evaluation. Pharmacokinetic analysis of DCE-MRI time-course data allows estimation of quantitative imaging biomarkers such as Ktrans(rate constant for plasma/interstitium contrast reagent (CR) transfer) and ve (extravascular and extracellular volume fraction). However, the use of quantitative DCE-MRI in clinical prostate imaging islimited, with uncertainty in arterial input function (AIF, i.e., the time rate of change of the concentration of CR in the blood plasma) determination being one of the primary reasons. In this multicenter data analysis challenge to assess the effects of variations in AIF quantification on estimation of DCE-MRI parameters, prostate DCE-MRI data acquired at one center from 11 prostate cancer patients were shared among nine centers. Each center used its site-specific method to determine the individual AIF from each data set and submitted the results to the managing center. Along with a literature population averaged AIF, these AIFs and their reference-tissue-adjusted variants were used by the managing center to perform pharmacokinetic analysis of the DCE-MRI data sets using the Tofts model (TM). All other variables including tumor region of interest (ROI) definition and pre-contrast T1 were kept the same to evaluate parameter variations caused by AIF variations only. Considerable pharmacokinetic parameter variations were observed with the within-subject coefficient of variation (wCV) of Ktrans obtained with unadjusted AIFs as high as 0.74. AIF-caused variations were larger in Ktrans than ve and both were reduced when reference-tissue-adjusted AIFs were used. The parameter variations were largely systematic, resulting in nearly unchanged parametric map patterns. The CR intravasation rate constant, kep (= Ktrans/ve), was less sensitive to AIF variation than Ktrans (wCV for unadjusted AIFs: 0.45 for kep vs. 0.74 for Ktrans), suggesting that it might be a more robust imaging biomarker of prostate microvasculature than Ktrans.

To assess the correlation between intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) metrics in hepatocellular carcinoma (HCC) and liver parenchyma.Twenty-five patients with HCC (M/F 23/2, mean age 58 years) underwent abdominal MRI at 1.5 or 3.0T, including IVIM-DWI (with 16 b-values) and DCE-MRI (3D FLASH sequence, mean temporal resolution of 2.3 sec). IVIM-DWI parameters (pseudodiffusion coefficient, D*, diffusion coefficient, D, and perfusion fraction, PF) were quantified in HCC lesions and liver parenchyma using a Bayesian fitting algorithm. DCE-MRI parameters (arterial flow, Fa , portal flow, Fp , total flow, Ft , mean transit time, MTT, distribution volume, DV, and arterial fraction, ART) were quantified using a dual-input single-compartment model. Correlations between IVIM-DWI and DCE-MRI parameters were assessed using a Spearman correlation test.Thirty-three HCC lesions (average size 5.0 ± 3.6 cm) were analyzed. D, D*, and PF were all significantly lower in HCC vs. liver (P 0.05). Significantly higher Fa and ART and lower Fp were observed in HCC vs. liver (P 0.001). Significant moderate to strong negative correlations were observed between ART and D* (r = -0.443, P = 0.028), ART and PF (r = -0.536, P = 0.006), ART and PFxD* (r = -0.655, P 0.001), Fa and PF (r = 0.455, P = 0.023), and Fa and PFxD* (r = -0.475, P = 0.018) in liver parenchyma. There was no significant correlation between IVIM-DWI and DCE-MRI metrics in HCC lesions.IVIM-DWI and DCE-MRI provide nonredundant information in HCC, while they correlate in liver parenchyma. These findings may be secondary to predominant portal inflow in the liver and tortuous vasculature and tissue heterogeneity in tumors. J. MAGN. RESON. IMAGING 2016;44:856-864.

To quantify hepatocellular carcinoma (HCC) perfusion and flow with the fast exchange regime-allowed Shutter-Speed model (SSM) compared to the Tofts model (TM). In this prospective study, 25 patients with HCC underwent DCE-MRI. ROIs were placed in liver parenchyma, portal vein, aorta and HCC lesions. Signal intensities were analyzed employing dual-input TM and SSM models. ART (arterial fraction), K trans (contrast agent transfer rate constant from plasma to extravascular extracellular space), v e (extravascular extracellular volume fraction), k ep (contrast agent intravasation rate constant), and τ i (mean intracellular water molecule lifetime) were compared between liver parenchyma and HCC, and ART, K trans, v e and k ep were compared between models using Wilcoxon tests and limits of agreement. Test–retest reproducibility was assessed in 10 patients. ART and v e obtained with TM; ART, v e , k e and τ i obtained with SSM were significantly different between liver parenchyma and HCC (p

To assess interplatform reproducibility of liver stiffness (LS) and spleen stiffness (SS) measured with magnetic resonance elastography (MRE) based on a 2D gradient echo (GRE) sequence.This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved study involved 12 subjects (five healthy volunteers and seven patients with liver disease). A multislice 2D-GRE-based MRE sequence was performed using two systems from different vendors (3.0T GE and 1.5T Siemens) on the same day. Two independent observers measured LS and SS on confidence maps. Bland-Altman analysis (with coefficient of reproducibility, CR), coefficient of variability (CV), and intraclass correlation (ICC) were used to analyze interplatform, intra- and interobserver variability. Human data were validated using a gelatin-based phantom.There was excellent reproducibility of phantom stiffness measurement (CV 4.4%). Mean LS values were 3.44-3.48 kPa and 3.62-3.63 kPa, and mean SS values were 7.54-7.91 kPa and 8.40-8.85 kPa at 3.0T and 1.5T for observers 1 and 2, respectively. The mean CVs between platforms were 9.2%-11.5% and 13.1%-14.4% for LS and SS, respectively, for observers 1 and 2. There was excellent interplatform reproducibility (ICC0.88 and CR36.2%) for both LS and SS, and excellent intra- and interobserver reproducibility (intraobserver: ICC0.99, CV2.1%, CR6.6%; interobserver: ICC0.97, CV and CR16%).This study demonstrates that 2D-GRE MRE provides platform- and observer-independent LS and SS measurements.

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for treatment efficacy in a multicenter randomized study comparing edoxaban monotherapy with a heparin/warfarin regimen for acute, symptomatic lower extremities deep vein thrombosis (DVT) treatment. We also used a direct thrombus imaging approach (DTHI, without the use of a contrast agent) to quantify fresh thrombus. We then sought to evaluate the reproducibility of the analysis methodology and applicability of using 3D magnetic resonance venography and direct thrombus imaging for the quantification of DVT in a multicenter trial setting. From 10 randomly selected subjects participating in the edoxaban Thrombus Reduction Imaging Study (eTRIS), total thrombus volume in the entire lower extremity deep venous system was quantified bilaterally. Subjects were imaged using 3D-T1W gradient echo sequences before (direct thrombus imaging, DTHI) and 5 min after injection of 0.03 mmol/kg of gadofosveset trisodium (magnetic resonance venography, MRV). The margins of the DVT on corresponding axial, curved multi-planar reformatted images were manually delineated by two observers to obtain volumetric measurements of the venous thrombi. MRV was used to compute total DVT volume, whereas DTHI was used to compute volume of fresh thrombus. Intra-class correlation (ICC) and Bland Altman analysis were performed to compare inter and intra-observer variability of the analysis. The ICC for inter and intra-observer variability was excellent (0.99 and 0.98, p

Imagenes axiales de TC que demuestran signos de obstruccion intestinal con dilatacion acentuada de asas de colon. notese la extension del material fecal impactado en el recto y colon distal como causa de la obstruccion, con una compresion extrinseca del higado asi como una importante dilatacion secundaria de la pelvis renal izquierda.

Objectives: Hepatocellular carcinoma (HCC) surveillance with biannual ultrasound is currently recommended for all patients with cirrhosis. However, clinical implementation of this “one-size-fits-all” approach is challenging as evidenced by its low application rate. We aimed to evaluate the cost-effectiveness of risk-stratified HCC surveillance strategies in patients with cirrhosis. Methods: A Markov decision-analytic modeling was performed to simulate a cohort of 50-year-old subjects with compensated cirrhosis. Risk-stratified HCC surveillance strategies was implemented, in which patients were stratified into high-, intermediate-, or low-risk groups by HCC risk biomarker–based scores and assigned to surveillance modalities tailored to HCC risk (2 non-risk-stratified and 14 risk-stratified strategies) and compared with non-stratified biannual ultrasound. Results: Quality-adjusted life expectancy gains for biannual ultrasound in all patients and risk-stratified strategies compared with no surveillance were 1.3 and 0.9–2.1 years, respectively. Compared with the current standard of biannual ultrasound in all cirrhosis patients, risk-stratified strategies applying magnetic resonance imaging (MRI) and/or ultrasound only in high- and intermediate-risk patients, without screening in low-risk patients, were cost-effective. Abbreviated MRI (AMRI) for high- and intermediate-risk patients had the lowest incremental cost-effectiveness ratio (ICER) of $2,100 per quality-adjusted life year gained. AMRI in intermediate- and high-risk patients had ICERs

The volvulus of the colon is a relatively common cause of colonic obstruction, mainly in the sigmoid colon, less frequent in the caecum, and rarely in the transverse colon. Multidetector tomography (MDCT) is able to establish the diagnosis showing dilated loops of proximal right and transverse colon, which depend on the time scale of evolution, with an abrupt transition site at the splenic flexure and a secondary torsion of the transverse colon mesentery. Volvulus of the transverse requires surgical detorsion in adults. Among the therapeutic options, simple detorsion or detorsion associated with a colopexy are included, but both have high rates of recurrence compared to resection techniques. Surgical resection of the involved segment is required prior to gangrene and perforation. Resection with or without primary anastomosis is the treatment of choice and prevents recurrence. The transverse colon volvulus is a disease of very low frequency and clinical diagnosis may be difficult. The management remains controversial. We stress that although many surgeons will never see a case of transverse colon volvulus, it should be considered as a differential diagnosis of intermittent abdominal pain or acute intestinal obstruction.

Background CT guided percutaneous biopsy of pulmonary lesions is a widely used technique. Aim To evaluate the yield and complication rate of CT-guided percutaneous core biopsy of pulmonary lesions. Material and methods A retrospective study of 153 consecutive lung biopsies performed in a 7-year period was undertaken. Patients and lesions characteristics were reviewed. The yield for the diagnosis of malignant and benign lesions and the complication rate were calculated. Lesion size and depth from the pleural surface were analyzed as potential predictive variables for occurrence of a false-negative diagnosis of malignancy. The final diagnosis was established by surgical biopsy of the lesion or clinical and imaging follow up. Results The mean age of patients was 66 ± 14 years and 55% were mole. The final diagnosis of the lesion was malignant in 139 and benign in 14 cases (prevalence of malignancy 90.8%). For the diagnosis of malignancy, the overall yield of the biopsy was 91.5%o with a sensitivity of 90.6%>. A specific diagnosis of benign lesions was obtained in 5 out of l4 biopsies (35%). We did not identify an association between the lesion size or depth and the rate of false-negative diagnosis of malignancy. The pneumothorax rate was 13.7%o (n = 21) and eight (38%) required drainage. The average lesion depth of patients that had a pneumothorax was significant greater than the cases without the complication. No major bleeding complications occurred. Conclusions Percutaneous CT-guided cutting needle biopsies of pulmonary lesions have an excellent diagnostic accuracy for malignant pulmonary lesions, at a low complication rate.

CT guided percutaneous biopsy of pulmonary lesions is a widely used technique.To evaluate the yield and complication rate of CT-guided percutaneous core biopsy of pulmonary lesions.A retrospective study of 153 consecutive lung biopsies performed in a 7-year period was undertaken. Patients and lesions characteristics were reviewed. The yield for the diagnosis of malignant and benign lesions and the complication rate were calculated. Lesion size and depth from the pleural surface were analyzed as potential predictive variables for occurrence of a false-negative diagnosis of malignancy. The final diagnosis was established by surgical biopsy of the lesion or clinical and imaging follow up.The mean age of patients was 66 ± 14 years and 55% were mole. The final diagnosis of the lesion was malignant in 139 and benign in 14 cases (prevalence of malignancy 90.8%). For the diagnosis of malignancy, the overall yield of the biopsy was 91.5%o with a sensitivity of 90.6%. A specific diagnosis of benign lesions was obtained in 5 out of l4 biopsies (35%). We did not identify an association between the lesion size or depth and the rate of false-negative diagnosis of malignancy. The pneumothorax rate was 13.7%o (n = 21) and eight (38%) required drainage. The average lesion depth of patients that had a pneumothorax was significant greater than the cases without the complication. No major bleeding complications occurred.Percutaneous CT-guided cutting needle biopsies of pulmonary lesions have an excellent diagnostic accuracy for malignant pulmonary lesions, at a low complication rate.

Echinococcal disease remains a major problem within some endemic areas. We report a case of a single primary echinococcal cyst located in the retroperitoneal space. A 54-year-old woman, born in a rural area of southern Chile, was admitted with a 3-month history of right hip pain and painful swelling of the gluteal region. Hidatid disease was confirmed with serologic test, radiological examinations and histo-pathology. There were no cysts in any other location. A percutaneous drainage was performed and antihelminthics were administered for 12 weeks and is now being closely followed up, with good response to therapy. Especially in the endemic areas hydatid cyst should be considered when evaluating retroperitoneal cystic masses.

Cavernous hemangioma of the rectum. Report of one case We report a 41 years old male with a history of hematochezia since childhood. A colonoscopy showed a highly vascularized submucosal lesion extending from the pectinate line to the distal sigmoid colon. Magnetic resonance showed a thickening of rectal wall with multiple vascular structures and phleboliths. The lesion was excised surgically. The postoperative period was uneventful. The pathological report disclosed a large rectal hemangioma. Key words: Hemangioma, hematochezia, rectum. Resumen El hemangioma rectal es una entidad infrecuente, con menos de 200 casos publicados en la literatura mundial. Se presenta un caso clinico, que debuta con rectorragia y es documentado con estudios endoscopicos e imagenologicos, siendo resuelto quirurgicamente. Palabras clave: Recto, hemangioma cavernoso, rectorragia, resonancia magnetica. Rev. Chilena de Cirugia. Vol 62 - No 4, Agosto 2010; pag. 412-414 CASOS CLINICOS *Recibido el 2 de Diciembre de 2009 y aceptado para publicacion el 20 de Enero de 2010.Correspondencia: Dr. Alvaro M. Zuniga D. Marcoleta 340, Santiago, Chile. E-mail: azuniga@med.puc.cl

Objetivo: Reportar la experiencia de biopsias percutaneas esplenicas con aguja tru-cut guiadas por imagenes. Materiales y Metodos: Revision retrospectiva de biopsias esplenicas con aguja tru-cut guiadas por ultrasonido (US) y tomografia computada (TC) realizadas en nuestro hospital desde Enero de 2005 a Abril de 2009. Resultados: Se identificaron un total de 13 procedimientos. La biopsia percutanea logro un diagnostico especifi co en 9 (69%) de las 13 intervenciones. Los diagnosticos fueron linfoma (n = 4), melanoma (n = 2), sarcoma (n = 1), hematopoyesis extramedular (n = 1) y criptococosis esplenica (n = 1). De las biopsias no diagnosticas 3 casos correspondieron a patologia neoplasica y uno a patologia benigna. Se reportaron 2 complicaciones (15%). Discusion: La biopsia esplenica percutanea guiada por imagenes con aguja tru-cut es un procedimiento util y seguro, capaz de determinar el diagnostico definitivo en la mayoria de los pacientes y evitar la mayoria de las esplenectomias diagnosticas.

Los tumores de intestino delgado (ID) son raros, representando aproximadamente 3-6% de las neoplasias del tubo digestivo. La E-TC es una técnica que combina las ventajas de la enteroclisis con las de la TC multicorte, con el potencial de demostrar alteraciones intraluminales, murales y extraintesti-nales. El objetivo de nuestro estudio fue evaluar el potencial diagnóstico de la E-TC en la detección de tumores de ID. En nuestra institución se realizaron 600 E-TC desde Enero del 2005 a Mayo del 2008. Un total de 22 pacientes (3,6 %) presentaron hallazgos tomográficos compatibles con tumores de ID, todos confirmados histológicamente. Los tumores encontrados en esta serie fueron; adenocarcinoma (n:4), linfoma (n:3), tumor carcinoide (n:3), tumor estromal gastrointestinal benigno (n:2), pólipos hamartomatosos (n: 2) y compromiso neoplásico secundario (n:8). Esta serie corrobora el valor de la E-TC como técnica de imagen de elección en la detección de tumores de ID, con la posibilidad de etapificación en el mismo procedimiento.