Diffusion weighted imaging in the liver

Diffusion weighted magnetic resonance imaging (DWI) is an imaging technique which provides tissue contrast by the measurement of diffusion properties of water molecules within tissues. Diffusion is expressed in an apparent diffusion coefficient (ADC), which reflects the diffusion properties unique to each type of tissue. DWI has been originally used in neuroradiology. More recently, DWI has increasingly been used in addition to conventional unenhanced and enhanced magnetic resonance imaging (MRI) in other parts of the body. The reason for this delay was a number of technical problems inherent to the technique, making DWI very sensitive to artifacts, which had to be overcome. With assessment of ADC values, DWI proved to be helpful in characterization of focal liver lesions. However, DWI should always be used in conjunction to conventional MRI since there is considerable overlap between ADC values of benign and malignant lesions. DWI is useful in the detection of hepatocellular carcinoma in the cirrhotic liver and detection of liver metastases in oncological patients. In addition, DWI is a promising tool in the prediction of tumor responsiveness to chemotherapy and the follow-up of oncological patients after treatment, as DWI may be capable of detecting recurrent disease earlier than conventional imaging. This review focuses on the most common applications of DWI in the liver

Computer-assisted solid lung nodule 3D volumetry on CT:influence of scan mode and iterative reconstruction: a CT phantom study

To evaluate the effect of high-resolution scan mode and iterative reconstruction on lung nodule 3D volumetry. Solid nodules with various sizes (5, 8, 10 and 12 mm) were placed inside a chest phantom. CT images were obtained with various tube currents, scan modes (conventional mode, high-resolution mode) and iterative reconstructions [0, 50 and 100 % blending of adaptive statistical iterative reconstruction (ASiR) and filtered back projection]. The nodule volumes were calculated using semiautomatic software and compared with the assumed volume from the nodules. The mean absolute and relative percentage error improved when using iterative reconstruction especially when using the conventional scan mode; however, this effect was not significant. Significant reduction in volume overestimation was observed when using high-resolution scan mode (P = 0.011). The high-resolution mode significantly reduces the volume overestimation of 3D volumetry. Iterative reconstruction shows a reduction in volume overestimation and error margin especially with the conventional scan mode; however, this effect was not significant

Increase in Volume of Ablation Zones during Follow-up Is Highly Suggestive of Ablation Site Recurrence in Colorectal Liver Metastases Treated with Radiofrequency Ablation

Purpose: To test the hypothesis that volume changes of ablation zones (AZs) on successive computed tomography (CT) scans could predict ablation site recurrences (ASRs) in patients with colorectal liver metastases treated by radiofrequency (RF) ablation. Materials and Methods: RF ablation was performed in 58 patients with 117 metastases. Metastasis volumes and AZ volumes were measured before RF ablation, 1 week after RF ablation (t1), and every 3 months in the first year after RF ablation (t2-t5). Volumetry was performed semiautomatically on CT scans by drawing freehand regions of interest in the portal venous phase on 2-mm-thickness slices. ASR was defined as contrast enhancement on follow-up imaging or by a hot spot on fludeoxyglucose F 18 positron emission tomography combined with computed tomography (FDG-PET/CT) scanning. Proportional volume change of an AZ was defined as the difference in volume percentages between two successive time points of measurement. Negative values represented a volume decrease, and positive values represented a volume increase. Intraobserver variability and interobserver variability were evaluated by using intraclass correlation coefficients (ICCs). Results: ASRs occurred in 15 patients with 27 AZs. An increase in volume occurred in 26 AZs (96%) with ASRs. AZs without ASR showed no volume increase. Although proportional volume changes at t1-t2 were not predictive for ASR, subsequent volume changes were predictive for ASR. Contrast-enhanced CT-based evaluation detected ASRs in 17 (63%) of 27 AZs, 7 (26%) of 27 AZs were negative, and there was doubt in 3 (11%) of 27 AZs. Intraobserver variability and interobserver variability were good (0.998 [95% confidence interval [CI] 0.996-0.999; P <.001] and 0.993 [95% CI 0.987-0.996; P <.001]). Conclusions: Volumetry of AZs is useful because a volume increase of an AZ during follow-up is highly suggestive of ASR. Negative volume changes of the AZ from t1-t2 were not correlated with the development of ASRs, but subsequent volume changes. were predictive for ASRs

Routine or on Demand Radiological Contrast Examination in the Diagnosis of Anastomotic Leakage After Esophagectomy

Background: To detect anastomotic leakage after esophagectomy in esophageal carcinoma patients, many surgeons perform a radiological contrast examination routinely. The aim of this retrospective study is to determine the clinical relevance of a routine contrast examination after esophagectomy and to evaluate criteria for contrast examination on demand. Methods: Data were obtained from 211 patients with cancer of the esophagus or gastro-esophageal junction who underwent an esophagectomy during the period 1991-2004. Retrospectively, we analyzed patients regarding anastomosis-related characteristics and clinical signs including sepsis, fever >= 39.0 degrees C, leukocytosis >= 20 x 10(9)/ml and pleural effusion. Results: Anastomotic leakage had appeared in 35 of the 211 patients. The clinical signs sepsis (odds ratio (OR) 6.72: 95% confidence interval (CI) (2.57-17.56); P = 39.0 degrees C and leukocytosis >= 20 x 10(9)/ml. J. Surg. Oncol. 2009:100:699-702. (C) 2009 Wiley-Liss, Inc

Is Roux-en-Y Choledochojejunostomy an Independent Risk Factor for Nonanastomotic Biliary Strictures After Liver Transplantation?

Biliary reconstruction using Roux-en-Y choledochojejunostomy has been suggested as a risk factor for the development of nonanastomotic biliary strictures (NAS) after liver transplantation. Roux-en-Y reconstruction, however, is preferentially used in patients transplanted for primary sclerosing cholangitis (PSC), and the disease itself is also associated with a higher incidence of NAS. The aim of this study was to determine whether Roux-en-Y reconstruction is really an independent risk factor for NAS. A series of 486 consecutive adult liver transplants were studied. Biliary reconstruction in patients transplanted for PSC was either by Roux-en-Y choledochojejunostomy or by duct-to-duct anastomosis, depending on the quality of the recipient's extrahepatic bile duct. Univariate and multivariate statistical analyses were used to identify risk factors for the development of NAS. The overall incidence of NAS was 16.5% (80/486). In univariate analyses, the following variables were significantly associated with NAS: PSC as the indication for transplantation, type of biliary reconstruction (Roux-en-Y versus duct-to-duct), and postoperative cytomegalovirus infection. After multivariate logistic regression analysis, PSC as the indication for transplantation (odds ratio, 2.813; 95% confidence interval, 1.624-4.875; P <0.001) and postoperative cytomegalovirus infection (odds ratio, 2.098; 95% confidence interval, 1.266-3.477; P = 0.004) remained as independent risk factors for NAS. Biliary reconstruction using Roux-en-Y choledochojejunostomy was not identified as an independent risk factor for NAS. In conclusion, the association between Roux-en-Y choledochojejunostomy and NAS observed in previous studies can be explained by the more frequent use of Roux-en-Y reconstruction in patients with PSC. Roux-en-Y reconstruction itself is not an independent risk factor for NAS. Liver Transpl 15:924-930, 2009. (C) 2009 AASLD

Hepatocellular Carcinoma in Tyrosinemia Type 1 Without Clear Increase of AFP

Patients with hereditary tyrosinemia type 1 have an elevated risk of developing hepatocellular carcinoma, especially if initiation of treatment with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexanedione is delayed. Hepatocellular carcinoma can usually be suspected when there are increased alpha(1)-fetoprotein levels and characteristic imaging features. The present case shows that a lack of a clear increase in alpha(1)-fetoprotein should still lead to consideration of liver transplantation when imaging features change

Non-invasive liver iron concentration measurement by MRI:Comparison of two validated protocols

In the non-invasive determination of the liver iron concentration several validated MRI methods are available, two of which are compared in this study. Twenty-eight patients were examined by MRI and evaluated by the methods of Kreeftenberg et al. [Kreeftenberg Jr HG, Mcoyaart EL, Huizenga JR, Sluiter WJ, Kreeftenberg Sr HG. Quantification of liver iron concentration with magnetic resonance imaging by combining T1-, T2-weighted spin echo sequences and a gradient echo sequence. Neth J Med 2000;56:133-7] and Gandon et al. [Gandon Y, Olivie D, Guyader D, et al. Non-invasive assessment of hepatic iron stores by MRI. Lancet 2004;363:357-62]. It is concluded that the latter shows a better inter- and intra-observer correlation and is more accurate because of the automated preselection of one of five sequences most sensitive in the estimated liver iron concentration range. In the Kreeftenberg method combining the results of three suboptimal sequences, leads to underestimation of the liver iron concentration. (C) 2008 Elsevier Ireland Ltd. All rights reserved

The impact of hepatic steatosis on liver regeneration after partial hepatectomy

<p>Background & Aim Experimental studies in animals have suggested that liver regeneration is impaired in steatotic livers. However, few studies have focused on the impact of steatosis in patients undergoing partial hepatectomy (PH). This study aims to determine the role of steatosis on liver regeneration in humans following PH. Methods Eighty-eight patients undergoing PH were included in this study. All patients underwent CT-scanning of the liver preoperatively and 7days after surgery. Additional CT-scans were performed 6months post-operatively. Preoperative and post-operative volumes of the total liver (TLV), future liver remnant (FLR) and liver remnant (LR) were measured on CT-scans. Regeneration indices (RI) were calculated at 7days and 6months using the formula: (Volume LRVolume FLR)/Volume FLRx100%. Based on histological examination of the resected part of the liver, patients were classified into three groups: (1) no steatosis, (2) mild steatosis (129%) and (3) moderate-to-severe steatosis (30%). Results The early RI (at day 7) was 40%, 24% and 20% for patients in group 1, 2 and 3 respectively. Late RI (at 6months) was 81% for group 1, 44% for group 2 and 22% for group 3 (P=0.019). At 7days, the LR represented 79%, 80% and 79% of the TLV for groups 13. At 6months, this was 93%, 92% and 79% respectively. Conclusion Although early RI after PH did not differ in patients with or without steatosis, the late RI in patients with moderate-to-severe steatosis was lower, suggesting that late liver regeneration is impaired in these patients.</p>