Acoustic radiation force impulse elastography of the liver: can fat deposition in the liver affect the measurement of liver stiffness?

Purpose  

The aim of this study was to compare acoustic radiation force impulse (ARFI) results between livers with and without fat deposition.     

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.     

Preoperative detection of colorectal liver metastases in fatty liver: MDCT or MRI?

Objective

To compare the diagnostic value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative detection of colorectal liver metastases in diffuse fatty infiltration of the liver, associated with neoadjuvant chemotherapy.

Materials and methods

Twenty preoperative tri-phasic MDCT (4-64-row, Siemens) and dynamic contrast-enhanced MRI (1.5 T or 3.0 T, Siemens) examinations of patients with colorectal cancer and liver metastases in diffuse steatosis were retrospectively evaluated. All patients underwent surgical resection for liver metastases (time interval 1-60 days). The amount of fatty infiltration of the liver was determined histopathologically by semi-quantitative percent-wise estimation and ranged from 25 to 75%.

Results

Overall, 51 metastases were found by histopathology of the resected liver segments/lobes. The size of the metastases ranged from 0.4 to 13 cm, with 18 (35%) being up to 1 cm in diameter. In the overall rating, MDCT detected 33/51 lesions (65%), and MRI 45/51 (88%). For lesions up to 1 cm, MDCT detected only 2/18 (11%) and MRI 12/18 (66%). One false positive lesion was detected by MDCT. Statistical analysis showed that MRI is markedly superior to MDCT, with a statistically significant difference (p < .001), particularly for the detection of small lesions (≤1 cm; p < .004). There was no significant difference between the two modalities in the detection of lesions > 1 cm.

Conclusion

For the detection of colorectal liver metastases after neoadjuvant chemotherapy and consecutive diffuse fatty infiltration of the liver, MRI is superior to MDCT, especially for the detection of small lesions.     

Measurement of liver T₁ and T₂ relaxation times in an experimental mouse model of liver fibrosis

Purpose:

To characterize changes in relaxation times of liver using quantitative magnetic resonance imaging (MRI) in an experimental mouse model of liver fibrosis. Quantitative MRI is a potentially robust method to characterize liver fibrosis. However, correlation between relaxation times and fibrosis stage has been controversial.

Materials and Methods:

Liver fibrosis was induced in male adult C57BL/6N mice (22–25 g; n = 12) by repetitive dosing of carbon tetrachloride (CCl₄). The animals were examined with a series of spin‐echo (SE) images with varying TRs and multiecho SE imaging sequence at 7 T before and 2, 4, 6, and 8 weeks after CCl₄ insult. Hepatic T₁ and T₂ values were measured. Histology was performed with hematoxylin‐eosin staining and Masson's trichrome staining.

Results:

Significant increase (P < 0.001) in hepatic T₁ was found at 2, 4, 6, and 8 weeks following CCl₄ insult as compared with that before insult. Meanwhile, hepatic T₂ at 2, 4, 6, and 8 weeks after CCl₄ insult was significantly higher (P < 0.001) than that before the insult. Liver histology showed collagen deposition, edema, and infiltration of inflammatory cells in livers with CCl₄ insult.

Conclusion:

Both longitudinal and transverse relaxation times may serve as robust markers for liver fibrosis. With the advent of single breath‐hold sequences for MR relaxometry, quantitative mapping of relaxation times can be routinely and reliably performed in abdominal organs and hence may be valuable and robust in detecting liver fibrosis at early phase and monitoring its progression. J. Magn. Reson. Imaging 2012;36:152–158. © 2012 Wiley Periodicals, Inc.     

Can contrast-enhanced ultrasonography replace multidetector-computed tomography in the detection of liver metastases from colorectal cancer?

Purpose

To compare the sensitivity and specificity of contrast-enhanced ultrasonography (CEUS) and 4-slice multidetector-computed tomography (MDCT) in the detection of liver metastases in patients with colorectal cancer (CRC).

Materials and methods

Candidates for this prospective study were 461 consecutive patients referred to the Department of Colorectal Surgery, Aarhus University Hospital with primary or local recurrence of CRC. The patients underwent liver ultrasonography (US), CEUS, MDCT and intraoperative ultrasonography (IOUS). Fine-needle biopsy was performed on all suspicious lesions. The examinations were interpreted blindly and the combination of US, CEUS, biphasic MDCT, IOUS, follow up and biopsy was the gold standard.

Results

Three hundred and sixty-five patients were included. All patients had undergone preoperative US, CEUS and MDCT and 65.5% had received IOUS. The gold standard found liver metastases in 54 patients (14.8%). Multidetector CT found significantly more metastases than CEUS in 15 (28%) of the patients (p = 0.02). In a patient-by-patient analysis MDCT had a non-significantly higher sensitivity in the detection of liver metastases compared to CEUS (0.89 versus 0.80, p = 0.06). The specificity of CEUS (0.98) was slightly better than that of MDCT (0.94) (p = 0.02).

Conclusion

Multidetector CT found significant more metastases than CEUS, and MDCT had in patient-by-patient analysis a non-significant better sensitivity (p = 0.06) in detecting liver metastases in patients with CRC.     

Measurement of the apparent diffusion coefficient in the liver: is it a reliable index for hepatic disease diagnosis?

Purpose The aim of this study was to determine the validity of the hepatic apparent diffusion coefficient (ADC) measurement. The influence of differences in measured location and administration of Buscopan (hyoscine butylbromide) for ADC were assessed. Materials and methods SENSE-DWI (b = 0, 500) was obtained before and after Buscopan administration to 30 patients suspected of having a liver tumor. In this sequence, respiration gating was employed, but cardiac triggering was not. ADC measurement was performed in the hepatic parenchyma of both right and left lobes in selected slices. A statistical analysis was performed to estimate the correlation among ADC, measured location, Buscopan, and pulse rate. The images were visually evaluated to categorize the subcardiac signal loss in the left lobe. Results The ADC showed higher values in the left lobe than in the right lobe in both pre- and postloaded studies (P < 0.001). In a comparison between ADCs in the pre- and postloaded studies, the differences were not significant in the left lobe (P = 0.93) or the right lobe (P = 0.41). No correlation was noted between ADCs and the pulse rate. Visual evaluation revealed that the subcardiac signal loss was more prominent in the postloaded study. Conclusion ADC measurement of the left hepatic lobe was far more incorrect than that of the right lobe if cardiac gating was not employed. The administration of Buscopan worsened the image quality of the left lobe and made visual evaluation difficult. This article was presented at the Japan Radiological Society meeting in 2005.     

MRI of the liver: Can true FISP replace HASTE?

PURPOSE: To determine the diagnostic accuracy of two fast breath-hold magnetic resonance (MR) imaging sequences, half-Fourier acquired single turbo spin-echo (HASTE) and true fast imaging with steady state precession (TrueFISP), for the detection and characterization of focal liver lesions MATERIALS AND METHODS: A total of 186 patients with suspected focal liver lesions were enrolled in this study. All patients underwent the same standardized study protocol including HASTE and TrueFISP. A consensus reading based on all available image data served as a standard of reference for classifying lesions into cysts, hemangiomas, focal nodular hyperplasia, or malignant/other lesions. All malignant lesions, as well as hepatic adenomas and abscesses, were histologically verified. Each separated by an eight-week interval, HASTE and TrueFISP images were retrospectively reviewed in random order for the detection and characterization of focal hepatic lesions. Finally, a receiver operating characteristic (ROC) analysis was calculated. RESULTS: HASTE images had an overall sensitivity of 0.86 and a specificity of 0.91, whereas TrueFISP showed an overall sensitivity and specificity of 0.79 and 0.83, respectively (p>0.1). CONCLUSION: Neither HASTE nor TrueFISP alone are sufficient for the detection and characterization of hepatic lesions.     

Can low-dose CT with iterative reconstruction reduce both the radiation dose and the amount of iodine contrast medium in a dynamic CT study of the liver?

Purpose

To investigate whether low-dose dynamic CT of the liver with iterative reconstruction can reduce both the radiation dose and the amount of contrast medium.

Materials and methods

This study was approved by our institutional review board. 113 patients were randomly assigned to one of two groups. Group A/group B (fifty-eight/fifty-five patients) underwent liver dynamic CT at 120/100 kV, with 0/40% adaptive statistical iterative reconstruction (ASIR), with a contrast dose of 600/480 mg I/kg, respectively. Radiation exposure was estimated based on the manufacturer's phantom data. The enhancement value of the hepatic parenchyma, vessels and the tumor-to-liver contrast of hepatocellular carcinomas (HCCs) were compared between two groups. Two readers independently assessed the CT images of the hepatic parenchyma and HCCs.

Results

The mean CT dose indices: 6.38/4.04 mGy, the dose-length products: 194.54/124.57 mGy cm, for group A/group B. The mean enhancement value of the hepatic parenchyma and the tumor-to-liver contrast of HCCs with diameters greater than 1 cm in the post-contrast all phases did not differ significantly between two groups (P > 0.05). The enhancement values of vessels in group B were significantly higher than that in group A in the delayed phases (P < 0.05). Two reader's confidence levels for the hepatic parenchyma in the delayed phases and HCCs did not differ significantly between the groups (P > 0.05).

Conclusions

Low-dose dynamic CT with ASIR can reduce both the radiation dose and the amount of contrast medium without image quality degradation, compared to conventional dynamic CT without ASIR.     

Detection of liver metastasis: is diffusion-weighted imaging needed in Gd-EOB-DTPA-enhanced MR imaging for evaluation of colorectal liver metastases?

Purpose

We compared diagnostic ability for detecting hepatic metastases between gadolinium ethoxy benzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) on a 1.5-T system, and determined whether DWI is necessary in Gd-EOB-DTPA-enhanced MRI for diagnosing colorectal liver metastases.

Materials and methods

We assessed 29 consecutive prospectively enrolled patients with suspected metachronous colorectal liver metastases; all patients underwent surgery and had preoperative Gd-EOB-DTPA-enhanced MRI. Overall detection rate, sensitivity for detecting metastases and benign lesions, positive predictive value, and diagnostic accuracy (Az value) were compared among three image sets [unenhanced MRI (DWI set), Gd-EOB-DTPA-enhanced MRI excluding DWI (EOB set), and combined set].

Results

Gd-EOB-DTPA-enhanced MRI yielded better overall detection rate (77.8?C79.0?%) and sensitivity (87.1?C89.4?%) for detecting metastases than the DWI set (55.9?% and 64.7?%, respectively) for one observer (P?<?0.001). No statistically significant difference was seen between the EOB and combined sets, although several metastases were newly detected on additional DWI.

Conclusions

Gd-EOB-DTPA-enhanced MRI yielded a better overall detection rate and higher sensitivity for detecting metastases compared with unenhanced MRI. Additional DWI may be able to reduce oversight of lesions in Gd-EOB-DTPA-enhanced 1.5-T MRI for detecting colorectal liver metastases.     

Changes in the phenotype of polymorphic plasma proteins after liver transplantation – new data and medico-legal consequences

The genetically inherited polymorphic plasma protein types have always been considered stable for lifetime in humans. Most of these proteins are synthetised in the liver. Phenotypes for 14 plasma proteins in donors and recipients of liver transplants prior to and after transplantation were determined in 15 patients who had undergone liver transplantation at the university hospitals Charité and Rudolf Virchow in Berlin. The plasma proteins investigated were HP, TF, GC, PI, ORM1, ITI, A2HS, PLG, FXIIIB, BF, C3, C6, C8 and FH. Evidence was provided of irreversible change from the recipient type to the donor type in at least one patient for all the systems investigated. This is the first time such data have been obtained for ITI, A2HS, C8 and FH. These results clearly support the point that the dogma of life-long stability of genetically determined protein phenotypes is merely of limited validity. Against the background of good long-term results of liver transplantation, there are consequences for the practice of legal medicine in the particular context of certification of parentage, identification and stain analysis. Received: 21 November 1997 / Received in revised form: 4 March 1998     

Hollow fiber–liquid phase microextraction of barbiturates in liver samples

Barbiturates, especially phenobarbital, are involved in intoxication cases in Brazil and other countries. Liver tissue can be a useful alternate specimen when blood is not available (decomposition, severe fire, and exsanguination cases). Because the liver is a very complex matrix, it is essential is to eliminate potential interfering substances in this specimen before instrumental analysis of target compounds. In recent years, novel strategies for sample preparation have gained acceptance in the field of analytical toxicology. The objective of this work was to develop a gas chromatography–mass spectrometry (GC–MS) method using hollow fiber–liquid phase microextraction (HF–LPME) for determination of barbiturates (phenobarbital, secobarbital, pentobarbital, and butalbital) in liver samples. An aliquot of homogenized and acidified liver in aqueous solution (equivalent to 50 mg tissue) was submitted to extraction by the use of a 9-cm hollow fiber. The fiber was filled with eucalyptus oil in its pores and its lumen was filled with a NaOH solution (pH 13; acceptor phase). After extraction in an ultrasonic bath for 5 min, the acceptor phase was withdrawn and derivatized in the injector port of the GC–MS with trimethylanilinium hydroxide for flash methylation. A totally “green chemistry” approach of the sample extraction was obtained, because relatively large amounts of organic solvent generally used for extraction could be substituted by an essential oil used as a supported liquid membrane for HF–LPME. This method was validated and successfully applied to liver samples collected from five deceased persons with previous history of exposure to barbiturates. Phenobarbital concentrations in the liver found in these actual cases ranged from 1.3 to 16.7 μg/g.     

Screening of biomarkers for liver adenoma in low-dose-rate γ-ray-irradiated mice

Purpose: Chronic low-dose-rate (20 mGy/day) γ-irradiation increases the incidence of hepatocellular adenomas (HCA) in female B6C3F1 mice. The purpose of this study is to identify potential serum biomarkers for these HCAs by a new approach.

Material and methods: Microarray analysis were performed to compare the gene expression profiles of HCAs from mice exposed to low-dose-rate γ-rays with those of normal livers from non-irradiated mice. From the differentially expressed genes, those for possibly secretory proteins were selected. Then, the levels of the proteins in sera were analysed by ELISA.

Results: Microarray analysis identified 4181 genes differentially expressed in HCAs (>2.0-fold). From these genes, those for α-fetoprotein (Afp), α-1B-glycoprotein (A1bg) and serine peptidase inhibitor Kazal type-3 (Spink3) were selected as the genes for candidate proteins. ELISA revealed that the levels of Afp and A1bg proteins in sera significantly increased and decreased, respectively, in low-dose-rate irradiated mice with HCAs and also same tendency was observed in human patients with hepatocellular carcinomas.

Conclusion: These results indicate that A1bg could be a new serum biomarker for liver tumor. This new approach of using microarray to select genes for secretory proteins is useful for prediction of novel tumor markers in sera.     

MRI of the liver and the pituitary gland in patients with beta-thalassemia major: does hepatic siderosis predict pituitary iron deposition?

Our objective was to study, in thalassemic patients, if hepatic siderosis evaluated by MRI could predict the pituitary iron overload. In 36 thalassemic patients (age range 6–44 years, mean age 21.7 years) the liver/fat ratio (L/F), the pituitary/fat ratio (P/F), the liver and pituitary T2 relaxation times were evaluated, by using a multiecho spin-echo sequence. Serum ferritin levels were measured and an extensive endocrine evaluation was performed. The L/F, the P/F and pituitary T2 showed a good correlation with serum ferritin (r=–0.55, r=–0.55 and r=–0.53, respectively; p<0.01). Liver T2 did not show significant correlation with serum ferritin. The variability of L/F explained only the 10.8% of the variability of pituitary T2 and of the P/F. When ferritin was added to the model it predicted only the 26.85% and the 30.8% of the variability of pituitary T2 and of the P/F, respectively. The P/F and pituitary T2 were lower in patients with hypogonadotropic hypogonadism (group 1) compared with those without pituitary dysfunction (group 2). No significant differences of L/F were found between the two groups. Hepatic iron overload evaluated by MR is a poor predictor of pituitary siderosis. The MR studies of the pituitary gland might be necessary to evaluate the pituitary iron overload. Electronic Publication     

Evaluation of the diagnostic value of a venous phase in CT angiography of the extremities in the setting of trauma: is vein imaging in vain?

Purpose

This study examined the value of including a venous phase in addition to the initial arterial phase in the CT angiography evaluation of extremity trauma.

Methods

CT studies from 157 patients (average age 38 years, age range 18–89 years, male 83%, female 17%) were obtained for trauma to the upper or lower extremity with both arterial and venous phases and retrospectively reviewed. The detection rate and type of vascular injury were evaluated by using the arterial phase alone and compared to the detection rate when interpreting the arterial and venous phases together.

Results

Arterial injury was identified in 35 cases (22%), and venous injury was identified in seven cases (5%). Four cases of discrepant diagnoses were identified between image interpretation of the arterial phase alone and interpretation using both phases, all of which were venous injuries that were visible only on the venous phase. None of the four cases of venous injury required a change in surgical management. Overall, no significant difference in diagnosis between the two methods of image interpretation (arterial phase alone, arterial and venous phases) was discovered (p > 0.125; CI 95%).

Conclusions

The use of a venous phase in the CT angiography evaluation of extremity trauma does not add significant arterial diagnostic or clinical management value despite its potential of increasing the diagnostic detection rate of venous injury.

     

Can Doppler sonography grade the severity of hepatitis C-related liver disease?

OBJECTIVE: Many authors have claimed that Doppler sonography indexes are of value in grading and assessing diffuse liver disease. However, there is much controversy regarding the reliability and reproducibility of these techniques. We performed a prospective study to evaluate whether these methods can grade disease in a well-stratified cohort of patients with hepatitis C virus (HCV)-related liver disease. SUBJECTS AND METHODS: Sixty-five patients with biopsy-proven HCV-related liver disease were recruited, and Doppler sonography was performed by one operator. The patients were classified into one of the following three groups on the basis of the Ishak-modified histologic activity index (HAI) fibrosis (F) and necroinflammatory (NI) scores: mild hepatitis (F < or = 2 and NI < or = 3), moderate or severe hepatitis (3 < or = F < 6 or NI > or = 4), or cirrhosis (F = 6/6). We measured the following Doppler indexes: main hepatic artery peak velocity (Vmax) and resistive index, main portal vein peak velocity (Vmax), and maximal portal vein diameter and circumference that allowed calculation of the portal vein congestive index (portal vein area and portal vein velocity). The ratio of the hepatic artery velocity (Vmax) to the portal vein velocity (Vmax) was also calculated, and the phasicity (triphasic, biphasic, or monophasic) of the hepatic veins of each patient was recorded. We also measured the maximal spleen length longitudinally. RESULTS: A total of 65 patients with liver disease (mild hepatitis, n = 20; moderate or severe hepatitis, n = 25; cirrhosis, n = 20) with biopsy-proven HCV-related liver disease were studied. Optimal hepatic arterial traces were obtained in only 30 patients and portal vein circumference in 18 patients. No significant differences were observed in the Doppler indexes with increasing severity of liver disease. Five (29%) of 17 patients with mild hepatitis had an abnormal hepatic vein trace (i.e., biphasic or monophasic) compared with 11 (55%) of 20 patients with moderate or severe hepatitis and 12 (60%) of 20 patients with cirrhosis. The only index to show a significant intergroup difference was splenic length (analysis of variance, p < 0.001), but there was still overlap between the groups. CONCLUSION: Doppler-derived indexes, which have previously been recommended for the assessment of severity in chronic liver disease, are difficult to reproduce reliably and therefore have a limited clinical role in the noninvasive assessment of hepatic fibrosis or inflammation.     

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.

     

How does alteration of hepatic blood flow affect liver perfusion and radiofrequency-induced thermal lesion size in rabbit liver?

The purpose of this study was to test the hypothesis that decreasing liver perfusion in rabbits results in an increase in thermal lesion size and that these effects can be accurately monitored using magnetic resonance imaging (MRI). We additionally tested the hypothesis that the increase in thermal lesion size would depend on the particular vessel or vessels occluded (hepatic artery, portal vein, or both). Using an Institutional Animal Care and Use Committee approved protocol, 20 New Zealand white rabbits were randomly assigned to four treatment groups (five in each group): control and ligation of portal vein (PV), hepatic artery (HA), or both PV and HA (HAPV). Surgical ligation of the appropriate vessel was performed under general anesthesia. Immediately after ligation, the rabbits were placed in a 0.2-T open MR system, and an 18-G copper radiofrequency (RF) electrode with a 2-cm exposed tip was inserted into the liver. RF was applied for 10 minutes with the tip temperature maintained at 90 degrees +/- 2 degrees C. Before and after ablation, perfusion data were obtained for 90 seconds using 30 3-second sequential single oblique-slice fast imaging with steady-state progression (FISP) acquisitions after injection of gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) via the inferior vena cava. Postablation scanning included axial and oblique turbo spin-echo (TSE) T2-weighted (T2w), STIR, and Gd-enhanced T1w sequences. Lesion size was determined perpendicular to the RF electrode using software calipers on the imager. The rabbits were sacrificed after completion of the post-therapy scans, and their livers were harvested for histologic analysis. The liver showed a mean increase in signal amplitude (SA) of 76% 24 seconds after Gd contrast injection in the control group. After contrast injection, the SA increased to a mean of only 66% in the group with ligated hepatic arteries, with no difference in the time to peak compared with the control group. No significant SA increase over baseline could be found in the groups with ligated PV or ligated PV and HA. T2-weighted images demonstrated the highest lesion-to-liver contrast-to-noise ratios (CNRs; mean -5.5) on postprocedure images, followed by STIR images (mean -2.2) in the control group. The lesions were poorly delineated on the Gd-enhanced images. Average maximum lesion sizes (mean +/- 95% confidence interval) were 22 +/- 4.3 mm after ligation of PV, 22 +/- 2.6 mm after ligation of both PV and HA, 14 +/- 2.0 mm after ligation of HA, and 13 +/- 1.9 mm in the control group. We accept the hypothesis that the diameter of the region of coagulation necrosis achieved by standardized RF ablation in the liver increases with reduced organ perfusion and that this effect can be accurately monitored using MRI. The major factor influencing the size of the coagulation area is the portal venous flow. Occlusion of the hepatic artery alone does not significantly increase lesion size. T2w sequences are best suited for postprocedure imaging due to the high lesion-to-liver CNR in rabbits with normal hepatic perfusion. J. Magn. Reson. Imaging 2001;13:57-63.