Complications of loco-regional therapy in the liver—spectrum of imaging findings by CT and MRI

The aim of this study was to discuss the appearance of common complications from loco-regional therapy of primary and secondary malignant liver neoplasms on cross-sectional imaging. Knowledge of common complications is important for the safe performance of loco-regional therapy (LRT) and for the interpretation of post-LRT follow-up imaging. With careful patient selection, LRT represents an effective and safe treatment of primary and secondary hepatic malignancies; however, complications related to LRT methods infrequently lead to additional morbidity.     

The effect of gadoxetic acid enhancement on lesion detection and characterisation using T₂ weighted imaging and diffusion weighted imaging of the liver

Objectives

To evaluate the effect of gadoxetic acid enhancement on the detection and characterisation of focal hepatic lesions on T₂ weighted and diffusion weighted (DW) images.

Methods

A total of 63 consecutive patients underwent T₂ weighted and DW imaging before and after gadoxetic acid enhancement. Two blinded readers independently identified all of the focal lesions using a five-point confidence scale and characterised each lesion using a three-point scale: 1, non-solid; 2, indeterminate; and 3, solid. For both T₂ weighted and DW imaging, the accuracies for detecting focal lesions were compared using the free-response receiver operating characteristic analysis; the accuracies for lesion characterisation were compared using the McNemar test between non-enhanced and gadoxetic acid-enhanced image sets. For hepatic lesions ≥1 cm, the lesion-to-liver contrast-to-noise ratio (CNR) and the apparent diffusion coefficient (ADC) were compared in the non-enhanced and enhanced image sets using the generalised estimating equations.

Results

For both T₂ weighted and DW images, the accuracies for detecting focal lesions (p≥0.52) and those for lesion characterisation (p≥0.63) did not differ significantly between the non-enhanced and enhanced image sets. The lesion-to-liver CNR was significantly higher on enhanced DW images than on non-enhanced DW images (p=0.02), although the difference was not significant for T₂ weighted imaging (p=0.65). The mean ADC values of lesions did not differ significantly on enhanced and non-enhanced DW imaging (p=0.75).

Conclusion

The acquisition of T₂ weighted and DW images after administration of gadoxetic acid has no significant effect on the detection or characterisation of focal hepatic lesions, although it improves the lesion-to-liver CNR on DW images.Various contrast agents have been developed and utilised for MRI of the liver in order to facilitate the detection and characterisation of focal hepatic lesions. Gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, Primovist^®; Bayer Schering Pharma, Berlin, Germany) is a recently developed, liver-specific contrast agent. As it has combined extracellular and hepatocyte-specific properties, gadoxetic acid can provide functional information regarding the cellular composition of focal hepatic lesions on hepatobiliary phase imaging as well as haemodynamic information on dynamic MRI following bolus injection. These properties of gadoxetic acid have been reported to improve the accuracy of liver MRI for lesion detection and characterisation [1-7].By contrast, these advantages of gadoxetic acid-enhanced liver MRI are obtained with increased examination time, as delayed scanning approximately 20 min after contrast administration is necessary for optimal hepatobiliary phase imaging [4,5,7-9]. Among the pulse sequences commonly acquired for clinical liver MRI, T₂ weighted and diffusion weighted (DW) imaging are frequently performed using a respiratory-triggered method in order to improve image quality [10-12], thus a lengthy acquisition time is required. To shorten the examination time for gadoxetic acid-enhanced MRI, it has been proposed to perform respiratory-triggered T₂ weighted and DW imaging during the interval between dynamic T₁ weighted imaging and the hepatobiliary phase imaging [7,13,14]. However, this modification in the MRI protocol is only feasible if the administration of gadoxetic acid does not degrade the image quality and provides comparable image quality and accuracy to non-enhanced imaging.Although previous studies have demonstrated that gadolinium-enhanced T₂ weighted images improve the conspicuity of focal hepatic lesions compared with unenhanced T₂ weighted images [15,16], these studies used non-specific extracellular contrast agents. Considering the different properties of extracellular contrast agents and gadoxetic acid, these results might not be easily applied to gadoxetic acid-enhanced MRI.Therefore, the purpose of our study was to evaluate the effect of gadoxetic acid on lesion detection and characterisation using T₂ weighted and DW imaging.     

Chronological evaluation of liver enhancement in patients with chronic liver disease at Gd-EOB-DTPA-enhanced 3-T MR imaging: does liver function correlate with enhancement?

Purpose  

To investigate the chronological relationship between scan delay and liver enhancement for the hepatobiliary phase on Gd-EOB-DTPA-enhanced MRI and evaluate the effects of liver function on liver enhancement.     

Non-FDG imaging of atherosclerosis: Will imaging of MMPs assess plaque vulnerability?

Acute ruptures of atherosclerotic plaques with subsequent occlusion account for the vast majority of clinical events such as myocardial infarction or stroke. New imaging approaches focusing on the visualization of inflammation in the vessel wall could emerge as tools for individualized risk assessment and prevention of events. To this end, PET employing ¹⁸F-fluorodeoxyglucose (FDG) has recently been introduced for the first clinical trials. Although this approach nicely visualizes plaques inflammation questions remain with respect to if and how this inflammatory signal can be employed for predicting individual plaque rupture. Molecular imaging of proteases such as matrix-metalloproteinases (MMPs) involved in several steps in plaque progression driving plaques into vulnerable, rupture-prone states seems a promising alternative approach. This review introduces and discusses the vulnerable plaque concept, animal models with human-like plaque ruptures and the potential of a FDG versus a non-FDG MMP-targeted strategy to image rupture-prone plaques.     

Nondiffuse fatty infiltration of the liver: does the uptake of iron-oxide increase or decrease at SPIO-enhanced MR imaging?

Purpose

To clarify whether the uptake of SPIO increases or decreases in areas of fatty change compared with surrounding areas of nonfatty change at SPIO-enhanced MR imaging.

Materials and methods

Approval for this retrospective study was obtained from our institutional review board. This study included 14 patients with nondiffuse fatty infiltration of the liver who underwent SPIO-enhanced MR imaging. Additionally, 30 patients without nondiffuse fatty infiltration of the liver were also evaluated.

Results

Among 14 patients, areas of fatty change showed relatively high signal intensity in 7 patents, indicating decreased uptake of SPIO in areas of fatty change. In these 7 patients, 4 had mild cirrhosis and 3 did not have cirrhosis. The mean percentage of signal intensity loss (42%) of fatty areas was significantly lower (p < 0.007) than that of adjacent areas of nonfatty change (52%). In the remaining 7 of 14 patients, areas of fatty change showed relatively low signal intensity, indicating increased uptake of SPIO in areas of fatty change. Among these 7 patients, 6 had advanced cirrhosis. The mean percentage of signal intensity loss (47%) of fatty areas was significantly higher (p < 0.008) than that of adjacent areas of nonfatty change (31%).

Conclusion

The uptake of SPIO generally decreased in areas of fatty change compared with normal liver parenchyma at SPIO-enhanced MR imaging. However, in patients with advanced cirrhosis, areas of fatty change shows relatively low signal intensity because the uptake of SPIO in surrounding areas of nonfatty change severely decreased probably due to liver fibrosis.     

Non-invasive detection of liver fibrosis: Is superparamagnetic iron oxide particle-enhanced MR imaging a contributive technique?

The purpose of our study was to evaluate the ability of superparamagnetic iron oxide (SPIO)-enhanced MR imaging to detect liver fibrosis in patients with chronic liver disease and to compare the findings with histopathological data. Sixty-seven patients with chronic hepatitis (n=58) or focal nodular hyperplasia (FNH; n=9) were studied using a 1.5-T MR system. The protocol included proton density-weighted, T2-weighted spin-echo (SE) and fast SE (FSE) sequences before and after SPIO administration and T2*-weighted gradient-recalled-echo (GRE) sequences after SPIO. Pre- and post-contrast T2-weighted and T2*-weighted sequences were retrospectively evaluated by three independent observers for evidence of non-tumor hypersignal intensities. Three liver patterns were considered: thick reticulations; thin reticulations; and/or multiple areas of hypersignal intensities. Unenhanced or enhanced patterns were compared with histopathological specimens, which had been obtained by percutaneous biopsy of the right lobe within a maximum of 12 months of MR examination. Liver fibrosis was histologically graded using a five-level scale (F0–F4), according to the METAVIR classification. Histopathology demonstrated significant fibrosis (F2–F4) in 57 patients, non-significant fibrosis in 1 patient (F1), and normal liver surrounding FNH in 9 patients (F0). After SPIO administration, at least one pattern of non-tumor hypersignal intensities was seen in 43 (76%) of the 57 patients with F≥2 with good agreement (kappa=0.68) compared with 2 (20%) of the 10 F0/1 patients (p<0.01). Attenuated non-homogeneous liver-signal intensities with persistent thick reticulations, thin reticulations, or multiple areas of hypersignals were observed in, respectively, 30, 52, and 56% of patients with F≥2 with moderate agreement (kappa=0.51). Before SPIO, MR images were positive in 21 of 57 (37%) F≥2 and zero F0/1 patients. Post-contrast proton-density-weighted and T2*-weighted GRE were the most sensitive sequences for detecting non-tumor hypersignal intensities. In patients with chronic liver diseases, SPIO-enhanced MR imaging exhibits non-tumor hypersignal intensities indicative of liver fibrosis by decreasing the signal from the non-fibrotic areas where Kupffer cells are present. Electronic Publication     

Science to Practice: Can MR imaging replace liver biopsy for the diagnosis of early fibrosis?

A method that could be used to accurately assess portal venous pressure would be valuable when diagnosing portal hypertension, evaluating patient prognosis, and monitoring the progress of therapy. Baik et al have suggested that a qualitative noninvasive Doppler US parameter can be used to monitor therapy of portal hypertension. Further clinical investigation is needed to confirm these results and to determine whether hepatic venous Doppler waveform tracings can be used to monitor patient response to therapy. Ongoing research suggests that microbubble contrast agents may enable a more quantitative noninvasive estimate of intravascular pressures with US.     

Treatment response classification of liver metastatic disease evaluated on imaging. Are RECIST unidimensional measurements accurate?

The purpose of this study was to evaluate the accuracy of unidimensional measurements (response evaluation criteria in solid tumors, RECIST) compared with volumetric measurements in patients with liver metastases undergoing chemotherapy. Forty-four patients with newly diagnosed liver lesions underwent three MRI examinations at treatment initiation, during chemotherapy, and immediately post-treatment. Measurements based on RECIST guidelines and volume calculations were performed on the “target” lesions (TLs). The two methods were in agreement in 64/77 of patients and 253/301 of individual lesions classification in response categories (“good” agreement, Cohen kappa = 0.735 and 0.741, respectively). In 16.88% of the comparisons the two methods stratified patients to a different response category; 27.6% of TLs did not follow the response category of the patient in whom lesions were located. The actual volume of TLs differs from the calculated volume of a sphere with the same diameter. Our study supports the use of volumetric techniques that may overcome certain disadvantages of unidimensional measurements.     

Resovist enhanced MR imaging of the liver: Does quantitative assessment help in focal lesion classification and characterization?

Purpose:

To improve characterization of focal liver lesions by a prospective quantitative analysis of percentage signal intensity change, in dynamic and late phases after slow (0.5 mL/s) Resovist administration.

Materials and Methods:

Seventy‐three patients were submitted on clinical indication to MR examination with Resovist. Signal intensity of 92 detected focal lesions (5–80 mm) were measured with regions of interest and normalized to paravertebral muscle in arterial, portal, equilibrium and T1/T2 late phases, by two observers in conference. Five values of percentage variations per patient were obtained and statistically evaluated.

Results:

The enhancement obtained on dynamic study is more suitable in hemangiomas and focal nodular hyperplasias than in adenomas and hepatocellular carcinomas. To discriminate benign versus malignant lesions on late‐phase‐T2‐weighted images, a cutoff = ?26%, allowed sensitivity and specificity values of 97.4% and 97.7%, respectively. Area under the receiver operating characteristic (ROC) curve was 0.99. To differentiate hemangioma versus all other focal liver lesions, on late‐phase‐T1‐weighted images, a cutoff = +40% permitted sensitivity and specificity values of 90.5% and 98.0%, respectively. Area under the ROC curve was 0.98.

Conclusion:

Late phase quantitative evaluation after slow Resovist administration, allows to differentiate malignant from benign hepatic masses and hemangiomas from all the others focal liver lesions, on T2‐/T1‐weighted acquisitions, respectively. J. Magn. Reson. Imaging 2009;30:1012–1020. © 2009 Wiley‐Liss, Inc.

     

Diagnosis of liver metastases: Can diffusion-weighted imaging (DWI) be used as a stand alone sequence?

Objectives

To evaluate if diffusion-weighted MRI (DWI) can replace gadolinium-enhanced MRI (Gd-MRI) for diagnosing liver metastases. The diagnostic accuracy of both techniques alone and in combination are compared.

Materials and methods

Sixty-eight patients with histologically proven primary extrahepatic tumors were included in this retrospective study. Lesions included 62 metastases and 130 benign lesions. Three image sets (unenhanced T1 and T2/gadolinium enhanced T1 (Gd-MRI), DWI and combination of both) were reviewed independently by 3 observers. The areas under the receiver operating characteristic curves (A_z), sensitivity and specificity for the 3 image sets were compared. The standard of reference was either histopathology or multi-modality and clinical follow-up.

Results

Pooled data showed higher diagnostic accuracy for the combined set (A_z = 0.93) compared to Gd-MRI (p = 0.001) and DWI (p < 0.0001). No difference was found between the performance of Gd-MRI and DWI (p = 0.09). Sensitivity for the combined set was higher than Gd-MRI (p = 0.0003) and DWI (p = 0.0034). Specificity for DWI was lower than Gd-MRI (p < 0.0001) and the combined set (p < 0.0001).

Conclusion

The diagnostic performance of DWI is equal to that of Gd-MRI. DWI alone can be used in patients where gadolinium contrast administration is not allowed. Combination of Gd-MRI and DWI significantly increases diagnostic accuracy.     

Fused 99m-Tc-GSA SPECT/CT imaging for the preoperative evaluation of postoperative liver function: can the liver uptake index predict postoperative hepatic functional reserve?

Purpose  

To evaluate the role of hepatic asialoglycoprotein receptor analysis in the preoperative estimation of postoperative hepatic functional reserve.     

The spectrum of imaging appearances of müllerian duct anomalies: focus on MR imaging

Müllerian duct anomalies (MDAs) are the result of incomplete development, vertical or lateral fusion, or absorption of the müllerian ducts. The range of anomalies includes uterovaginal agenesis or hypoplasia, unicornuate uterus, uterus didelphys, bicornuate uterus, septate uterus, and arcuate uterus. Correct diagnosis and classification of these anomalies are essential because pregnancy outcomes and treatment options vary between the types of anomaly. Furthermore, early identification of MDAs helps to avoid prolonged symptomatic periods and the complications that may subsequently arise, such as infertility, endometriosis, and neoplasm. Although many of these abnormalities are initially diagnosed by ultrasound or hysterosalpingography, MR imaging is the most accurate noninvasive modality available for classification of the various anomalies because of its better anatomic assessment compared with other diagnostic modalities. Familiarity with the wide variety of MDA presentations can help in the planning of appropriate treatment.     

Trans-caval trans-jugular liver biopsy—a technical modification of trans-jugular liver biopsy

Objective:

To (a) describe the technical modification of trans-caval TJLB and (b) review our series of nine cases.

Methods:

We performed a retrospective review of all trans-caval TJLBs performed; we assessed indications for the procedure, technical success, complications, adequacy of specimen and histological positivity.

Results:

The technical success rate of the procedure was 9/9 (100%); the minor complication rate was 1/9 (11%), adequate specimen was obtained in all cases and a histological diagnosis was achieved in 8/9 (89%) cases.

Conclusion:

This preliminary report suggests that trans-caval modification of TJLB is a relatively safe procedure that may be useful in cases where conventional TJLB is infeasible.

Advances in knowledge:

(a) We describe the technique of trans-caval TJLBs and report our findings in the largest series of published cases. (b) Trans-caval TJLB is relatively safe and can be used to increase the success rates of conventional TJLB.Trans-jugular liver biopsy (TJLB) is an established technique in patients unsuitable for a percutaneous trans-abdominal liver biopsy. TJLB procedure involves biopsy of the liver parenchyma through trans-jugular venous access, with the biopsy needle placed in the right hepatic vein (commonly described) or the middle or left hepatic veins. However, a TJLB may be not technically feasible in a small subset of cases where hepatic venous cannulation is not possible, owing to unsuitable hepatic venous anatomy, occluded hepatic veins [Budd–Chiari syndrome (BCS)] or markedly shrunken liver. In such cases, a technical modification of TJLB, called a direct trans-caval TJLB, can be performed. In this study, we (a) describe the technical modification of the trans-caval TJLB and (b) review the results of a series of nine cases where the trans-caval TJLB was carried out.