Mi Hee Lee

Planning Sonography to Assess the Feasibility of Percutaneous Radiofrequency Ablation of Hepatocellular Carcinomas

OBJECTIVE The objective of our study was to evaluate the feasibility rate and the reasons for infeasibility of percutaneous radiofrequency ablation of hepatocellular carcinomas (HCCs) at planning sonography. MATERIALS AND METHODS We retrospectively evaluated 248 patients who had been referred for planning sonography at our department between October 2005 and February 2006. We reviewed the radiologic reports of 256 planning sonography examinations in terms of the rate of feasible cases and the reasons for infeasibility. The reasons for infeasibility were classified in six categories: an inconspicuous tumor, an inadequate electrode path, an organ vulnerable to collateral thermal damage, a tumor that was too large or too many tumors, and a high risk of the heat sink effect. In addition, we assessed the treatment modality for the patients who were determined to have HCCs for which percutaneous radiofrequency ablation was not feasible. RESULTS In 141 (55%) of the 256 planning sonography examinations, percutaneous radiofrequency ablation was feasible. The remaining 115 (45%) planning sonography examinations revealed that radiofrequency ablation was not a feasible procedure. The reasons for infeasibility included an inconspicuous tumor in 77 patients (55.8%), an inadequate electrode path in 33 patients (23.9%), an organ vulnerable to collateral thermal damage in 14 patients (10.1%), a tumor that was too large or too many tumors in eight patients (5.8%), a high risk of the heat sink effect in five patients (3.6%), and a portal vein thrombosis in one patient (0.7%). One reason for infeasibility was found in 96 patients, two reasons in 19 patients, and four reasons in one patient. Seventy (61.9%) of 113 patients for whom radiofrequency ablation was not feasible underwent transcatheter arterial chemoembolization as an alternative treatment. CONCLUSION In approximately half of the patients for whom percutaneous radiofrequency ablation of HCC is requested, the procedure is not feasible, mainly due to inconspicuous tumors, at planning sonography. Additional objective criteria for assessing the feasibility of radiofrequency ablation and therapeutic strategies according to the reasons for infeasibility should be investigated further.

Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI

To examine the differential features of combined hepatocellular and cholangiocarcinoma (HCC‐CC) from mass‐forming intrahepatic cholangiocarcinoma (ICC) on gadoxetic acid‐enhanced MRI.

Detection of hepatocellular carcinoma in gadoxetic acid-enhanced MRI and diffusion-weighted MRI with respect to the severity of liver cirrhosis

Background As gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) have been widely used for the evaluation of hepatocellular carcinoma (HCC), it is clinically relevant to determine the diagnostic efficacy of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Purpose To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Material and Methods A total of 189 patients with 240 HCCs (≤3.0 cm) (Child-Pugh A, 81 patients with 90 HCCs; Child-Pugh B, 65 patients with 85 HCCs; Child-Pugh C, 43 patients with 65 HCCs) underwent DWI and gadoxetic acid-enhanced MRI at 3.0 T. A gadoxetic acid set (dynamic and hepatobiliary phase plus T2-weighted image) and DWI set (DWI plus unenhanced MRIs) for each Child-Pugh class were analyzed independently by two observers for detecting HCCs using receiver-operating characteristic analysis. The diagnostic accuracy and sensitivity were calculated. Results There was a trend toward decreased diagnostic accuracy for gadoxetic acid and DWI set with respect to the severity of cirrhosis (Child-Pugh A [mean 0.974, 0.961], B [mean 0.904, 0.863], C [mean 0.779, 0.760]). For both observers, the sensitivities of both image sets were highest in Child-Pugh class A (mean 95.6%, 93.9%), followed by class B (mean 83.0%, 77.1%), and class C (mean 60.6%, 60.0%) (P < 0.05). Conclusion In HCC detection, the diagnostic accuracy and sensitivity for gadoxetic acid-enhanced MRI and DWI were highest in Child-Pugh class A, followed by Child-Pugh class B, and Child-Pugh class C, indicating a tendency toward decreased diagnostic capability with the severity of cirrhosis.

Differentiation of an Intrapancreatic Accessory Spleen from a Small (<3-cm) Solid Pancreatic Tumor: Value of Diffusion-weighted MR Imaging

PURPOSE To evaluate the value of diffusion-weighted (DW) imaging in differentiation of an intrapancreatic accessory spleen (IPAS) from a small (<3 cm) solid pancreatic tumor. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and informed consent was waived. Twenty patients with IPAS and 22 patients with small solid pancreatic tumors were included. All patients underwent abdominal magnetic resonance (MR) imaging with DW and gadoxetic acid-enhanced imaging. Qualitative (signal intensity) and quantitative (signal intensity and apparent diffusion coefficient [ADC]) evaluations were performed by two observers. Fisher exact test and Mann-Whitney U test were used for comparing groups. RESULTS Compared with the spleen, the IPAS showed isointensity more frequently than did small pancreatic tumors on T2-weighted images (95% [19 of 20] vs 41% [nine of 22]), arterial phase images (100% [20 of 20] vs 18% [four of 22]), portal phase images (100% [20 of 20] vs 23% [five of 22]), late phase images (100% [20 of 20] vs 41% [nine of 22]), and DW images with b value of 0 sec/mm(2) (100% [20 of 20] vs 9% [two of 22]), b value of 100 sec/mm(2) (95% [19 of 20] vs 27% [six of 22]), and b value of 800 sec/mm(2) (100% [20 of 20] vs 27% [six of 22]), with significant differences (P < .01). The means of the absolute value of relative signal intensity and ADC ratio on DW images of IPAS were significantly lower and closer to zero than those of pancreatic tumors (P < .05). Visual assessment of the similarity between pancreatic lesion and spleen on DW images for diagnosis of IPAS yielded diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 95% (40 of 42), 100% (20 of 20), 91% (20 of 22), 91% (20 of 22), and 100% (20 of 20), respectively, for observer 1 and 90% (38 of 42), 95% (19 of 20), 86% (19 of 22), 86% (19 of 22), and 95% (19of 20), respectively, for observer 2. CONCLUSION In addition to conventional morphologic MR imaging, DW imaging can be used as a tool for differentiating IPAS from solid pancreatic tumors. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112765/-/DC1.

Fusion imaging-guided percutaneous biopsy of focal hepatic lesions with poor conspicuity on conventional sonography.

The purpose of this study was to evaluate the effectiveness of real‐time fusion imaging (sonography combined with computed tomography or magnetic resonance imaging) for percutaneous sonographically guided biopsy of focal hepatic lesions with poor sonographic conspicuity.

Imaging features of small (≤3 cm) pancreatic solid tumors on gadoxetic-acid-enhanced MR imaging and diffusion-weighted imaging: an initial experience

OBJECTIVE The objective was to determine imaging features that distinguish small (≤3cm) solid pancreatic adenocarcinoma, neuroendocrine tumor (NET) and solid pseudopapillary tumor (SPT) on gadoxetic-acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighed imaging (DWI). MATERIALS AND METHODS Twenty-four adenocarcinomas, 10 NETs and 8 SPTs were retrospectively included. Two radiologists analyzed morphologic features, signal intensity of the tumors on MR images including DWI (b=800) and dynamic enhancement pattern with consensus. Tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed. RESULTS All adenocarcinomas had an ill-defined margin and irregular shape, and more frequently had pancreatic duct dilatation compared with other tumors (P<.05). All SPTs and all but one of the adenocarcinomas (95.8%) had no arterial enhancement with progressively increased enhancement, whereas seven NETs (70%) had arterial enhancement with progressively decreased enhancement (P<.01). The mean value of tumor-to-parenchyma ratio on arterial and portal phases was significantly higher for NETs, and the mean value of tumor ADCs was significantly lower for SPTs than for other tumors (P<.05). CONCLUSIONS Gadoxetic-acid-enhanced MRI may aid in differentiation between small adenocarcinomas, NETs and SPTs based on morphologic features with dynamic enhancement pattern in adenocarcinomas, dynamic enhancement pattern with tumor-to-parenchyma ration on arterial and portal phases in NETs, and dynamic enhancement pattern with lower ADC value in SPTs.

HIGH SIGNAL INTENSITY OF THE POSTERIOR PITUITARY GLAND ON T1-WEIGHTED MR IMAGES: Correlation with plasma vasopressin concentration to water deprivation

Purpose: To evaluate the effect of water deprivation on the signal intensity of the posterior pituitary gland on T1-weighted MR images and correlate the signal intensity with the plasma vasopressin concentration. Material and Methods: Fifteen rabbits were studied: Group 1 (n=10) was deprived of water for 9 days and Group 2 (n=5) was replenished water for 7 days after 7-day water deprivation. MR imaging and plasma vasopressin measurement by radioimmunoassay were made before and after water deprivation and replenishment. Sequential changes of the signal intensity ratio of the posterior lobe to the pons and plasma vasopressin concentration were correlated. Results: Before water deprivation, the hyperintense posterior lobe was demonstrated in all rabbits. During water deprivation, the signal intensity ratio decreased and vasopressin concentration increased gradually. On the contrary, the signal intensity ratio increased and vasopressin concentration decreased with water replenishment. The signal intensity ratio correlated well with the plasma vasopressin concentration (p<0.05). Conclusion: There was a negative, linear correlation between the signal intensity ratio of the posterior pituitary gland on T1-weighted MR images and plasma vasopressin concentration to water deprivation. The results support that the high signal intensity of the posterior pituitary gland on T1-weighted MR images is attributed to the normal content of vasopressin-neurosecretory granules.

Differentiating Focal Eosinophilic Infiltration from Metastasis in the Liver with Gadoxetic Acid-Enhanced Magnetic Resonance Imaging

Objective To determine the most useful findings of gadoxetic acid-enhanced 3.0 Tesla (T) MRI for differentiating focal eosinophilic infiltration (FEI) from hepatic metastasis with verification of their usefulness. Materials and Methods Pathologically or clinically proven 39 FEIs from 25 patients and 79 hepatic metastases from 51 patients were included in the study. Gadoxetic acid-enhanced 3.0T MRI was performed in all cancer patients. Size differences measured between T2-weighted and hepatobiliary-phase images for lesions > 1 cm and morphologic findings (margin, shape, signal intensity on T1- and T2-weighted images, enhancement pattern on dynamic images, and target appearance on hepatobiliary-phase images) were compared between two groups via Students t test as well as univariate and multivariate analyses. Diagnostic predictive values of two observers for differentiating two groups were assessed before (session 1) and after (session 2) recognition of results. Results Mean size difference (2.1 mm) in FEIs between the two images was significantly greater than for metastases (0.7 mm) (p < 0.05). An ill-defined margin and isointensity on T1-weighted images were independently significant morphologic findings (p < 0.05) for differentiating the two groups. All observers achieved a higher diagnostic accuracy in session 2 (97% and 98%) than session 1 (92% and 89%) with statistical significance in observer 2 (p < 0.05). All observers had significantly higher sensitivities (95%) and negative predictive values (NPVs) (98%) in session 2 than in session 1 (sensitivity, 74% in two observers; NPV, 89% and 88%) (p < 0.05). Conclusion With the size change, an ill-defined margin and isointensity on T1-weighted images are the most useful findings for differentiating FEI from hepatic metastasis on gadoxetic acid-enhanced 3.0T MRI.

Gadoxetic acid-enhanced fat suppressed three-dimensional T1-weighted MRI using a multiecho dixon technique at 3 tesla: emphasis on image quality and hepatocellular carcinoma detection.

To compare the image quality between T1 high‐resolution isotropic volume examination using the multi‐echo Dixon technique (mDixon‐eTHRIVE) and that using spectrally adiabatic inversion recovery (SPAIR‐eTHRIVE) in gadoxetic acid‐enhanced liver MRI, and to evaluate the detectability of hepatocellular carcinoma (HCC) on mDixon‐eTHRIVE.

Liver MRI at 3.0 tesla: comparison of image quality and lesion detectability between single-source conventional and dual-source parallel radiofrequency transmissions.

Objective To prospectively and intraindividually compare liver magnetic resonance imaging (MRI) using single-source and dual-source parallel radiofrequency (RF) transmissions at 3.0-T for image quality, lesion detectability, and lesion contrast. Methods Ninety-nine patients with 139 liver lesions underwent liver MRI at 3.0-T. Two radiologists performed a consensus review of T2-weighted images (T2WI), heavily T2WI (HT2WI), gadoxetic acid–enhanced hepatobiliary images, and diffusion-weighted imaging using single-source and dual-source RF transmissions with regard to image quality and lesion detectability. Contrast ratios between liver lesions and liver parenchyma were also calculated. Results Image quality was better with dual-source than with single-source at T2WI and HT2WI (P < 0.05), but lesion detectabilities were similar for all sequences. There was no significant difference in mean contrast ratios for all sequences (P > 0.05). Conclusion Dual-source RF transmission provides a better image quality with T2WI and HT2WI than with single-source. However, 2 techniques showed similar lesion detectability.