Portal Venous Images Research Articles

Reproducibility of CT-Based Hepatocellular Carcinoma Radiomic Features across Different Contrast Imaging Phases: A Proof of Concept on SORAMIC Trial Data.

Simple SummaryRadiomics has been reported to have potential for correlating with clinical outcomes. However, handcrafted radiomic features (HRFs)—the quantitative features extracted from medical images—are limited by their sensitivity to variations in scanning parameters. Furthermore, radiomics analyses require big data with good quality to achieve desirable performances. In this study, we investigated the reproducibility of HRFs between scans acquired with the same scanning parameters except for the imaging phase (arterial and portal venous phases) to assess the possibilities of merging scans from different phases or replacing missing scans from a phase with other phases to increase data entries. Additionally, we assessed the potential of ComBat harmonization to remove batch effects attributed to this variation. Our results show that the majority of HRFs were not reproducible between the arterial and portal venous phases before or after ComBat harmonization. We provide a guide for analyzing scans of different imaging phases.Handcrafted radiomic features (HRFs) are quantitative imaging features extracted from regions of interest on medical images which can be correlated with clinical outcomes and biologic characteristics. While HRFs have been used to train predictive and prognostic models, their reproducibility has been reported to be affected by variations in scan acquisition and reconstruction parameters, even within the same imaging vendor. In this work, we evaluated the reproducibility of HRFs across the arterial and portal venous phases of contrast-enhanced computed tomography images depicting hepatocellular carcinomas, as well as the potential of ComBat harmonization to correct for this difference. ComBat harmonization is a method based on Bayesian estimates that was developed for gene expression arrays, and has been investigated as a potential method for harmonizing HRFs. Our results show that the majority of HRFs are not reproducible between the arterial and portal venous imaging phases, yet a number of HRFs could be used interchangeably between those phases. Furthermore, ComBat harmonization increased the number of reproducible HRFs across both phases by 1%. Our results guide the pooling of arterial and venous phases from different patients in an effort to increase cohort size, as well as joint analysis of the phases.

Precision and reliability of liver iodine quantification from spectral detector CT: evidence from phantom and patient data

To comprehensively assess precision, reproducibility, and repeatability of iodine maps from spectral detector CT (SDCT) in a phantom and in patients with repetitive examination of the abdomen. Seventy-seven patients who underwent examination two (n = 52) or three (n = 25) times according to clinical indications were included in this IRB-approved, retrospective study. The anthropomorphic liver phantom and all patients were scanned with a standardized protocol (SSDE in patients 15.8mGy). In patients, i.v. contrast was administered and portal venous images were acquired using bolus-tracking technique. The phantom was scanned three times at three time points; in one acquisition, image reconstruction was repeated three times. Region of interest (ROI) were placed automatically (phantom) or manually (patients) in the liver parenchyma (mimic) and the portal vein; attenuation in conventional images (CI [HU]) and iodine map concentrations (IM [mg/ml]) were recorded. The coefficient of variation (CV [%]) was used to compare between repetitive acquisitions. If present, additional ROI were placed in cysts (n = 29) and hemangioma (n = 29). Differences throughout all phantom examinations were < 2%. In patients, differences between two examinations were higher (CV for CI/IM: portal vein, 2.5%/3.2%; liver parenchyma, -0.5%/-3.0% for CI/IM). In 80% of patients, these differences were within a ± 20% limit. Differences in benign liver lesions were even higher (68% and 38%, for CI and IM, respectively). Iodine maps from SDCT allow for reliable quantification of iodine content in phantoms; while in patients, rather large differences between repetitive examinations are likely due to differences in biological distribution. This underlines the need for careful clinical interpretation and further protocol optimization. • Spectral detector computed tomography allows for reliable quantification of iodine in phantoms. • In patients, the offset between repetitive examinations varies by 20%, likely due to differences in biological distribution. • Clinically, iodine maps should be interpreted with caution and should take the intra-individual variability of iodine distribution over time into account.

Enhancing contrast of magnetic resonance imaging in patients with liver cirrhosis: Conveyance times of Primovist in hepatobiliary system

Purpose: To determine transit times for excretion of gadoxetic acid (Gd-EOB-DTPA), a recent magnetic resonance imaging (MRI) contrast agent, in hepatobiliary system of patients with liver cirrhosis. Methods: Liver cirrhosis patients that underwent contrast MRI examination at Renai Hospital, Taipei City, Taiwan were included. The patients who have experienced contrast-enhanced abdominal MR examination after injection of 10 mL Gd-EOB-DTPA at 1.5-T MR from December 2009 to March 2011, were included retrospectively. The images were evaluated for the presence of contrast agent in intrahepatic bile ducts (IHD), common bile duct (CBD), gall bladder and duodenum. Results: The optimal time for arterial phase was from 15 s after injection while the optimal time for portal venous imaging was from 40 s after injection. Furthermore, the optimal time to observe changes was 20 min after contrast initiation of Gd-EOB-DTPA in 39 patients (83 %) in IHD and 37 patients (78.5 %) in CBD. Gall bladder reflux was visible in 26 patients (43 %), and duodenal excretion in 17 patients (36 %). After 30 min of contrast injection, Gd-EOB-DTPA could still be detected in 6 patients (13 %) in IHD and 7 patients (15 %) in CBD, while gall bladder reflux was visible in 10 patients (21 %), and duodenal excretion in 20 patients (55 %). Conclusion: The excretion of Gd-EOB-DTPA can be observed in liver cirrhosis patients. Keywords: Hepatocellular carcinoma, Magnetic resonance imaging (MRI), Gadoxetic acid, Common hepatic duct

Gadoxetic acid-enhanced MRI with MR cholangiography for the preoperative evaluation of bile duct cancer

To assess the diagnostic accuracy of gadoxetic acid-enhanced biliary MRI with MR cholangiography (MRC) in the preoperative evaluation of bile duct cancer (BDC) staging and resectability. Seventy-three patients with BDC who underwent gadoxetic acid-enhanced biliary MRI and MRC, were included in this study. Two abdominal radiologists evaluated the biliary MRI findings regarding the tumor extent, vascular involvement, lymph node metastasis, and tumor resectability. The results were compared with the surgical and pathology findings which were used as the standard reference. The diagnostic performance of the MRI was evaluated using receiver operating characteristics (ROC) analysis. In addition, to determine whether the hepatobiliary phase images had been successfully obtained, the enhancement percentage of the hepatic parenchyma was measured on the portal venous images (PVI) and hepatobiliary phase images (HBPI), respectively. The overall accuracy of the two reviewers for determining the tumor resectability was 61.6% and 83.5%, respectively. The Az values were 0.802 for reviewer 1 and 0.892 for reviewer 2 in the evaluation of the secondary biliary confluence tumor involvement and 0.773 for reviewer 1 and 0.846 for reviewer 2 in the evaluation of the intrapancreatic bile duct involvement. In the evaluation of the vascular involvement, the Az values were 0.718 and 0.906, respectively, for the hepatic artery evaluation and 0.55 and 0.88, respectively, for the portal vein evaluation. For assessment of lymph node metastasis, the overall accuracy was 69.6% and 79.7%, respectively. The mean enhancement percentages of hepatic parenchyma on PVI and HBPI were 39.3% and 65.9%, respectively (P % 0.05), and 49 of 73 patients (67.1%) showed higher enhancement percentage on HBPI than on PVI CONCLUSION: Gadoxetic acid-enhanced MRI with MRC is a reliable diagnostic method for assessing the tumor extent and resectability of BDC.

CONTRAST AGENT Gd‐EOB‐DTPA (EOB·Primovist®) FOR LOW‐FIELD MAGNETIC RESONANCE IMAGING OF CANINE FOCAL LIVER LESIONS

Contrast-enhanced magnetic resonance (MR) imaging with a new liver-specific contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA; EOB·Primovist®) was studied in 14 normal beagles and 9 dogs with focal liver lesions. Gd-EOB-DTPA accumulates in normally functioning hepatocytes 20 min after injection. As with Gd-DTPA, it is also possible to perform a dynamic multiphasic examination of the liver with Gd-EOB-DTPA, including an arterial phase and a portal venous phase. First, a reliable protocol was developed and the appropriate timings for the dynamic study and the parenchymal phase in normal dogs using Gd-EOB-DTPA were determined. Second, the patterns of these images were evaluated in patient dogs with hepatic masses. The optimal time of arterial imaging was from 15 s after injection, and the optimal time for portal venous imaging was from 40 s after injection. Meanwhile, the optimal time to observe changes during the hepatobiliary phase was from 20 min after injection. In patient dogs, 11 lesions were diagnosed as malignant tumors; all were hypointense to the surrounding normal liver parenchyma during the hepatobiliary phase. Even with a low-field MR imaging unit, the sequences afforded images adequate to visualize the liver parenchyma and to detect tumors within an appropriate scan time. Contrast-enhanced MR imaging with Gd-EOB-DTPA provides good demarcation on low-field MR imaging for diagnosing canine focal liver lesions.

Associated Vascular Injury in Patients with Bile Duct Injury During Cholecystectomy

Cholecystectomy remains one of the most commonly performed procedures in general surgery. Although the incidence, diagnosis, and treatment of bile duct (BD) injuries have been well described, studies characterizing associated vascular injuries are limited. The objective of this study was to analyze the frequency and management of associated vascular and BD injury after cholecystectomy. A total of 50 patients were referred to a tertiary institution for BD injuries from 1996 to 2010. Thirty-nine (78%) of the patients were female with the mean age of 49 years (range, 14 to 86 years). Seventy-five per cent of the injuries were Strasberg Type E. Nine patients (18%) had associated vascular injuries. Six patients had injuries to the right hepatic artery; in one patient, both the right and left hepatic arteries were damaged. Five patients had right portal vein injuries; three of these subsequently died. In conclusion, as a result of the high incidence of associated vascular injury, a thin-collimation CT angiogram and/or mesenteric angiogram with portal venous imaging should be considered as part of the preoperative evaluation in patients with BD injury.

Hepatocellular MR contrast agents: Enhancement characteristics of liver parenchyma and portal vein after administration of gadoxetic acid in comparison to gadobenate dimeglumine

PurposeTo investigate the enhancement characteristics of liver parenchyma and portal vein as well as the portal vein-to liver contrast in Gd-EOB-DTPA- and Gd-BOPTA-enhanced abdominal MRI. Materials and methodsThe local institutional review board approved this retrospective study. A total of 70 patients (30 female, 40 male) without relevant liver disease underwent either Gd-EOB-DTPA-enhanced (35 patients, dose 0.025mmol/kg) or Gd-BOPTA-enhanced (35 patients, dose 0.1mmol/kg) abdominal MRI. Signal-to-noise ratios (SNR) for the portal vein and the liver as well as portal vein-to-liver contrast-to-noise ratios (CNR) were calculated for three consecutive arterial phases, one portal venous phase and one delayed imaging phase. ResultsThe liver SNR showed higher values for the Gd-BOPTA group in the arterial and portal venous phases (statistically significant for the second and third arterial phase), while the liver SNR in the delayed phase was higher for the Gd-EOB-DTPA group. The portal venous SNR as well as the portal vein-to-liver CNR was higher in the Gd-BOPTA group in all imaging phases (statistically significant in all phases except for the first arterial phase). ConclusionThe enhancement of liver parenchyma and portal vein as well as the portal vein-to-liver contrast in the arterial and portal venous imaging phases were higher for patients receiving Gd-BOPTA compared with Gd-EOB-DTPA at the respective recommended doses. Gd-BOPTA might therefore enable better evaluation of the portal vein.

CT Portography with Gastric Variceal Volume Measurements in the Evaluation of Endoscopic Therapeutic Efficacy of Tissue Adhesive Injection into Gastric Varices: A Pilot Study

N-butyl-2-cyanoacrylate (NBCA) injection is used for treating gastric varices (GV). Determining the degree of obliteration of GV is not readily evident at endoscopy. The aim of this study was to evaluate CT portography with gastric variceal volume calculations to assess endoscopic therapeutic efficacy of NBCA injection. The study design is a retrospective series pilot study. The setting is a single, tertiary care academic medical center. Ten patients underwent esophagogastroduodenoscopy (EGD) with NBCA injection of GV and had biphasic CT scans performed before and after injection therapy. Based on portal venous images, 3D reconstruction and semi-automated volume calculations of GV were performed. Pre and post injection GV volume calculations were compared. The mean pre-procedure GV volume was 89.84 cm3. Eight patients had significant improvement in GV volume from pre-treatment versus post-treatment (95.65 cm3 vs. 49.65 cm3, P-value 0.04). Pre-procedure GV volume was not significantly different in patients treated for active hemorrhage versus no hemorrhage (101.66 cm3 vs. 72.11 cm3, P-value 0.33). Two patients had a subsequent GV hemorrhage after NBCA injection. The mean residual GV volume in these patients versus those that did not re-bleed was significantly more (127.77 cm3 vs. 38.00 cm3, P-value 0.005). CT portography with measurement of GV volume is a potentially useful tool in determining the therapeutic efficacy NBCA injection of GV. Patients with higher residual GV volumes are at increased risk of hemorrhage and may benefit from repeat injection to reach ideal GV volumes.

Investigation of acute lower gastrointestinal bleeding with 16‐ and 64‐slice multidetector CT†

We evaluated the usefulness of 16- and 64-slice multidetector CT (MDCT) in the detection of a bleeding site in acute lower gastrointestinal tract (GIT) haemorrhage by conducting a retrospective study of cases of presumed acute lower GIT haemorrhage imaged with CT in two teaching hospitals in an 11-month period. The patients underwent contrast enhanced CT using either a 16 or 64 MDCT. No oral contrast was used. One hundred milliliters of non-ionic intravenous contrast agent was injected at 4.5 mL/s, followed by a 60 mL saline flush at 4 mL/s through a dual head injector. Images were acquired in arterial phase with or without non-contrast and portal phase imaging with 16 x 1.5 mm or 64 x 0.625 mm collimation. Active bleeding was diagnosed by the presence of iodinated contrast extravasation into the bowel lumen on arterial phase images with attenuation greater than and distinct from the normal mucosal enhancement or focal pooling of increased attenuation contrast material within a bowel segment on portal-venous images. Further management and final diagnosis was recorded. Fourteen patients and 15 studies were reviewed. CT detected and localized a presumed bleeding site or potential causative pathology in 12 (80%) of the patients. Seven of these were supported by other investigations or surgery, while five were not demonstrated by other modalities. Eight patients had mesenteric angiography, of which only four corroborated the site of bleeding. CT did not detect the bleeding site in three patients, of which two required further investigation and definitive treatment. We propose that MDCT serves a useful role as the initial rapid investigation to triage patients presenting with lower GIT bleeding for further investigation and management.

Detection of Neuroendocrine Liver Metastases with MnDPDP-Enhanced MRI

Purpose: The sensitivity of computerised tomography (CT) in detecting neuroendocrine liver metastases is variable and three-phase imaging is advocated. However, patients are often young and may require prolonged follow-up, thus a technique that avoids radiation exposure would be desirable. Our purpose was to assess the diagnostic performance of MRI, before and after administration of mangafodipir trisodium (MnDPDP), in the detection of neuroendocrine liver metastases. Methods: Patients who had undergone single-phase or multi-phase contrast-enhanced MD-CT for neuroendocrine liver metastases were invited to have MRI. Two independent observers made quantitative measurements (number and size of lesions). All measurements were made on each available CT phase and all MRI sequences independently, and repeated after an interval to assess reproducibility. The final number of lesions was agreed on by consensus of three observers. A qualitative assessment (contrast and spatial resolution) and preferred modality were agreed on by consensus. Results: 265 lesions were detected by consensus in 11 patients. Non-contrast CT was available in 4/11, arterial phase in 6/11 and portal phase in 10/11 patients. When compared with the consensus number of lesions, MD-CT identified 17% on non-contrast, 44% on arterial and 43% on portal venous imaging. Lesion detection on MRI was 48% on T₁W, 52% on T₂W and 92% on MnDPDP-MRI. The number of lesions detected on MnDPDP-MRI was closest to the final consensus reading (variance = 0.994, p = 0.0027). The reproducibility of lesion size measurements was best on MnDPDP-MRI (variance = 0.033, p = 0.0021). The preferred modality subjectively was MnDPDP-MRI in 9/11 cases and T₂W MRI in 2/11. Conclusion: MRI is a robust technique in the demonstration of neuroendocrine liver metastases. It is highly reproducible in both detecting the number and measuring the size of lesions. We recommend T₂W MRI and MnDPDP-MRI in detection and follow-up of neuroendocrine liver metastases.

Abstract No. 195: Transsplenic Splenoportography in Paediatric Portal Hypertension: A Safe and Useful Tool

Over the past two decades, transsplenic splenoportography (TSSP) for portal venous imaging has been replaced with arterial portography, CT, US and MRI due to its potential for bleeding complications. However, these procedures can be equivocal and lack the ability to provide dynamic information about the portal venous flow. Purpose: To use our institutional experience with TSSP to illustrate its usefulness and safety in the evaluation of paediatric portal hypertension.

Triple-phase MDCT of hepatocellular carcinoma.

The purpose of this study was to describe the appearances of hepatocellular carcinoma including intralesional contrast washout using a triple-phase liver protocol on an MDCT scanner. Fifty-one patients with newly diagnosed hepatocellular carcinoma underwent standardized triple-phase CT using a multidetector scanner. Pathologic proof was obtained in 35 patients (69%); in 16 patients (31%), hepatocellular carcinoma was diagnosed on clinical and laboratory findings. Two radiologists independently reviewed the CT studies for the appearance and attenuation of the lesions. Intralesional washout of contrast material was evaluated subjectively and objectively. Statistical analysis was performed using Fisher's exact test to analyze the relationships between tumor appearance and alpha-fetoprotein level, tumor grade, and risk factor. Correlation between tumor size and appearance was analyzed using the Student's t test and Wilcoxon's rank sum test. The most common enhancement pattern for hepatocellular carcinoma was hypervascularity on hepatic arterial phase images with a mosaic pattern on both arterial and portal venous images; this finding was seen in 86% and 78% of lesions by the two observers, respectively. A hypervascular component was seen in 96% of lesions by both observers, and the observers recorded 86% and 63% of lesions as showing washout, respectively. Objective washout was present in 76% of lesions. Both subjective and objective washout correlated with an elevated alpha-fetoprotein level (p = 0.01). The appearances of hepatocellular carcinoma on images obtained using MDCT scanners are similar to those described for images obtained using single-detector helical scanners. However, the prevalence of hypervascular hepatocellular carcinoma on MDCT images is higher than previously described on single-detector helical images and most lesions showed washout on portal venous MDCT images.

MDCT of primary liver malignancies.

One of the major indications for abdominal CT is liver malignancies. Hepatocellular carcinoma (HCe) is the most common primary malignant hepatic neoplasm and its incidence is increasing. The HCC usually occurs as a complication of chronic liver disease and most often arises in patients with hepatic cirrhosis. The detection of HCC in patients with cirrhosis has been considered a technical challenge for CT for a long time, because cirrhosis alters both liver parenchymal characteristics as well as vascularization. Most HCCs are hypervascular lesions that typically enhance during the phase of maximum hepatic arterial enhancement; therefore, such lesions have often been difficult to detect with conventional CT of the liver, in which only portal venous phase imaging was performed because of the long scanning time. During the past decade, the introduction of helical CT technology has opened the door to new approaches to liver imaging. With its short acquisition time, spiral CT allows imaging the entire liver twice, before equilibrium: a hepatic arterial dominant phase and portal venous phase of enhancement [1]. The results of several studies have demonstrated that this biphasic approach to scanning greatly improves the detection of HCC. Because of the vascular nature of these lesions, there is evidence that a higher number of HCC nodules are detected when images are acquired in dual-phase CT compared with portal venous imaging alone [2, 3]. The advent of multidector-row CT (MDCT) has offered considerable advantages; they include improved temporal resolutions, improved spatial resolutions in the z axis, and longer anatomic coverage. As a result, we can scan the abdomen within reasonable breath-hold times which decrease respiratory and motion artifacts and provide higher image quality. Excellent 3D data sets can also be produced with thin collimation improving multiplanar imaging and the ability to perform CT angiography of the liver and mesenteric vessels [4] which can be important in patients candidate for hepatic resection, liver transplantation, or transarterial chemoembolization. In this respect, CT porto-angiography is probably superior to classic angiography. The CT angiography provides a complete picture of complex collateralizations of portal vein in potential liver transplantation recipients (Fig. 1). With the improvement in technology an inevitable evolution in scanning techniques is needed to maximize the benefit of new imaging capabilities. The issues of contrast medium administrations need to be revisited including the optimal timing, the total volume, the rate of administration, and the ideal iodine concentration.

Hepatic arterial and portal venous phase helical CT in patients treated with transcatheter arterial chemoembolization for hepatocellular carcinoma: added value of unenhanced images.

To evaluate the additional diagnostic value of unenhanced computed tomographic (CT) images in the depiction of viable tumor in patients who were treated with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) and followed up with biphasic helical CT that included the acquisition of unenhanced images. We performed helical CT (with unenhanced, arterial, and portal phases) in 54 patients who had been treated with TACE for HCC. Image analysis was first performed with only those images obtained in the arterial and portal venous phases of helical CT. A second analysis was then performed with unenhanced images, arterial images, and portal venous images that focused on the additional value of unenhanced images. The value of additional unenhanced images was evaluated by means of interobserver agreement (kappa statistic) and receiver operating characteristic (ROC) analysis. The two readers detected 128 and 129 lesions. Unenhanced images were valuable for 32 of 129 lesions (23 patients) for reader 1 and for 29 of 128 lesions (21 patients) for reader 2. Although there was no significant difference between biphasic CT alone and biphasic CT with unenhanced images, results of ROC analysis showed higher diagnostic performance with biphasic CT with unenhanced images than with biphasic CT alone for detecting viable tumor. The study data demonstrate the diagnostic value of unenhanced images interpreted in conjunction with biphasic CT images for follow-up of patients who have previously been treated with TACE for HCC.