Francesco Agnello

High-b-Value Diffusion-weighted MR Imaging of Benign Hepatocellular Lesions: Quantitative and Qualitative Analysis

PURPOSE To analyze the signal intensity (SI) of benign hepatocellular lesions in high-b-value diffusion-weighted (DW) magnetic resonance (MR) images and to compare the apparent diffusion coefficient (ADC) values of focal nodular hyperplasias (FNHs) with those of hepatocellular adenomas (HCAs). MATERIALS AND METHODS This retrospective study was approved by institutional review board, with waiver of informed consent. Inclusion criteria were consecutive patients with diagnosed FNH or HCA who underwent MR imaging with a DW sequence of the liver at three b values, 0, 150, and 600 sec/mm2. The final study population included 67 patients (seven men, 60 women) with 90 hepatocellular lesions (54 FNHs, 36 HCAs). The mean ADC was compared between the lesions and the liver. Receiver operating characteristic analysis was performed to evaluate the diagnostic value of ADC for differentiating HCAs and FNHs. RESULTS The mean ADC value of all FNHs and HCAs was significantly lower than that of the liver (P=.004). An ADC ratio below 15% was observed in 50 of 54 (93%) FNHs and in 29 of 36 (81%) HCAs. The mean ADC value of FNHs was significantly higher than that of HCAs (P<.001). The area under the receiver operating characteristic curve was 0.760. With a cutoff value of 1.37×10(-3) mm2/sec, the sensitivity and specificity for differentiating HCA from FNH were 70% and 76%, respectively. There was no significant difference in ADC values between HCA subtypes. The SI of most FNHs and HCAs (78 of 90, 87%) increased with increasing b values, whereas none showed a decrease in SI with increasing b values. When the DW MR criteria for benign and malignant liver tumors were applied, 44 of 90 (49%) lesions would have been considered malignant lesions, whereas the other lesions (46 of 90, 51%) would have been considered indeterminate. CONCLUSION On DW MR images, benign hepatocellular lesions often show findings that suggest restricted diffusion.

Small solid renal masses: Characterization by diffusion-weighted MRI at 3 T

AIM To describe the appearance of small solid renal lesions (≤3 cm) on diffusion-weighted magnetic resonance imaging (MRI) and to determine whether ADC measurements may help to differentiate benign from malignant small solid renal masses. METHODS AND MATERIALS Thirty-five patients with 47 small renal masses (23 malignant, 24 benign) who underwent 3 T MRI of the kidney using diffusion-weighted sequences (b values of 0 and 1000 s/mm(2)) were retrospectively evaluated. Qualitative and quantitative analysis of diffusion-weighted images was performed. RESULTS Most lesions were hyperintense to kidney on high b-value diffusion-weighted images and hypointense on apparent diffusion coefficient (ADC) map. The mean ADC of the lesions was significantly lower than that of kidney (1.22 ± 0.3 versus 1.85 ± 0.12 mm(2)/s; p < 0.005). The mean ADC was significantly different between renal cell carcinomas (1.2 ± 0.01 mm(2)/s), metastases (1.25 ± 0.04 mm(2)/s), angiomyolipoma (1.07 ± 0.3 mm(2)/s) and oncocytomas (1.56 ± 0.08 mm(2)/s; p < 0.05). The mean ADC of clear cell renal cell carcinomas was significantly different from that of non-clear cell renal cell carcinomas (1.38 ± 0.34 versus 0.83 ± 0.34 mm(2)/s; p < 0.005). No significant difference was found between mean ADC of fat containing and minimal fat angiomyolipomas (1.06 ± 0.48 versus 1.11 ± 0.33 mm(2)/s). CONCLUSION Small solid renal masses are hyperintense on high b value and have different ADC values.

Hepatocellular carcinoma presenting at contrast-enhanced multi-detector-row computed tomography or gadolinium-enhanced magnetic resonance imaging as a small (≤2 cm), indeterminate nodule: growth rate and optimal interval time for imaging follow-up.

Objective The objective of the study was to measure growth rate and to determine the optimal interval time for imaging follow-up of hepatocellular carcinomas (HCCs) presenting at multi–detector-row computed tomography (MDCT) or magnetic resonance imaging (MRI) as small, indeterminate lesions. Methods We included patients with cirrhosis with HCC initially presenting as indeterminate lesion of 2 cm or less at MDCT or MRI August 2005 to August 2009 and with available imaging follow-up. Measures of tumor growth included tumor volume doubling time (TVDT), tumor percentual diameter increase, and tumor percentual volume increase. Results We examined 48 patients (mean age, 64 years) with 69 HCCs. At index examination, mean (SD) maximum transverse diameter and volume of lesions were 1.2 (SD, 0.3) cm and 0.6 (SD, 0.7) cm3, respectively. Median TVDT was 210 days. Tumors with follow-up longer than 365 days had significant increase in tumor percentual diameter increase and tumor percentual volume increase. Conclusions Median TVDT of 210 days suggests extended follow-up of 6 months for small, indeterminate liver nodules detected at MDCT or MRI.

Comparison between whole-body MRI with diffusion-weighted imaging and PET/CT in staging newly diagnosed FDG-avid lymphomas.

OBJECTIVES To compare whole body-MRI (WB-MRI) with diffusion-weighted imaging and FDG-PET/CT in staging newly diagnosed FDG-avid lymphomas. METHODS 68 patients (37 males, 31 females; median age 42 years; range 15-86 years) with histologically confirmed lymphoma (37 Classical Hodgkin, 16 Diffuse large B-cell, 10 Follicular, 5 Mantle cell) underwent both MRI and FDG-PET/CT before treatment. Ann Arbor stages obtained with WB-MRI and FDG-PET/CT were compared using Cohens k statistics. Moreover WB-MRI and FDG-PET/CT stages were compared with the pathological stages obtained after the diagnostic iter using also bone marrow and available biopsies if clinically indicated. RESULTS The agreement between WB-MRI and FDG-PET/CT was excellent. WB-MRI stage was equal to those of FDG-PET/CT in 62/68 patients (91.2%). There was an excellent agreement between WB-MRI stage and pathological stage (63/68 patients; 92.6%), and between FDG-PET/CT and pathological stage (64/68 patients; 94.1%). The differences between the stages were more frequent in the patients with Mantle cell lymphoma. CONCLUSIONS WB-MRI can be considered as a promising technique for FDG-avid lymphoma staging.

Enhancement pattern of small hepatocellular carcinoma (HCC) at contrast-enhanced US (CEUS), MDCT, and MRI: Intermodality agreement and comparison of diagnostic sensitivity between 2005 and 2010 American Association for the Study of Liver Diseases (AASLD) guidelines

OBJECTIVE To evaluate agreement between contrast-enhanced ultrasound (CEUS), multi-detector row computed tomography (MDCT) and magnetic resonance imaging (MRI) for the assessment of typical and atypical enhancement patterns of small hepatocellular carcinoma (HCC); and to compare diagnostic sensitivity of 2005 and 2010 American Association for the Study of Liver Diseases (AASLD) guidelines. MATERIALS AND METHODS Between January 2008 and December 2009, we included cirrhotic patients with newly diagnosed 10-20 mm HCC imaged at two contrast-enhanced imaging techniques among CEUS, MDCT, and MRI. Dynamic studies were reviewed by two radiologists to assess enhancement pattern. Percentage of cases with concordant findings and Cohen coefficient (k) were calculated. McNemars test was used to compare sensitivity between 2005 and 2010 AASLD guidelines. RESULTS There were 91 patients (69 M; 22 F; mean age, 68 years) with 96 HCCs, studied with a combination of CEUS and MDCT (n=59), CEUS and MRI (n=26), or MDCT and MRI (n=11). Intermodality agreement for assessment of tumor enhancement pattern was 67% (k=0.294, P=0.001). Typical enhancement pattern was detected coincidentally at two imaging modalities in 50 (52%) HCCs. Sensitivity for the diagnosis of HCC increased significantly using the 2010 AASLD (81/96 (84%) vs. 50/96 (52%), P<0.001). CONCLUSIONS Agreement between two imaging modalities for the detection of typical tumor enhancement pattern was reached in 52% of cases. The 2010 AASLD guidelines significantly increased the sensitivity for the diagnosis of HCC.

Imaging appearance of treated hepatocellular carcinoma

Surgical resection and imaging guided treatments play a crucial role in the management of hepatocellular carcinoma (HCC). Although the primary end point of treatment of HCC is survival, radiological response could be a surrogate end point of survival, and has a key role in HCC decision-making process. However, radiological assessment of HCC treatment efficacy is often controversial. There are few doubts on the evaluation of surgical resection; in fact, all known tumor sites should be removed. However, an unenhancing partial linear peripheral halo, in most cases, surrounding a fluid collection reducing in size during follow-up is demonstrated in successfully resected tumor with bipolar radiofrequency electrosurgical device. Efficacy assessment of locoregional therapies is more controversial and differs between percutaneous ablation (e.g., radiofrequency ablation and percutaneous ethanol injection) and transarterial treatments (e.g., conventional transarterial chemoembolization, transarterial chemoembolization with drug eluting beads and radioembolization). Finally, a different approach should be used for new systemic agent that, though not reducing tumor mass, could have a benefit on survival by delaying tumor progression and death. The purpose of this brief article is to review HCC imaging appearance after treatment.

Gadoxetate Disodium―Enhanced Magnetic Resonance Cholangiography for the Noninvasive Detection of an Active Bile Duct Leak After Laparoscopic Cholecystectomy

We report a case of an endoscopically confirmed biliary leak of the common hepatic duct after laparoscopic cholecystectomy that was prospectively diagnosed on gadoxetate disodium-enhanced magnetic resonance cholangiography. Whereas dynamic contrast-enhanced magnetic resonance images during the early vascular phases helped to rule out the causes of possible complications such as seroma, hematoma, or abdominal abscess, delayed hepatobiliary phase imaging was crucial for unequivocal diagnosis and location of the biliary leak. The diagnosis prompted therapeutic endoscopic retrograde cholangiography whereby a polytetrafluoroethylene-covered nitinol stent graft was successfully placed to repair the biliary injury.

Focal lesions in cirrhotic liver: what else beyond hepatocellular carcinoma?

Detection and characterization of focal lesions in the cirrhotic liver may pose a diagnostic dilemma. Several benign and malignant lesions may be found in a cirrhotic liver along with hepatocellular carcinoma (HCC), and may exhibit typical or atypical imaging features. In this pictorial essay, we illustrate computed tomography and magnetic resonance imaging findings of lesions such as simple bile duct cysts, hemangioma, focal nodular hyperplasia-like nodules, peribiliary cysts, intrahepatic cholangiocarcinoma, lymphoma, and metastases, all of which occur in cirrhotic livers with varying prevalences. Pseudolesions, such as perfusion anomalies, focal confluent fibrosis, and segmental hyperplasia, will also be discussed. Imaging characterization of non-HCC lesions in cirrhosis is important in formulating an accurate diagnosis and triaging the patient towards the most appropriate management.

Assessment of cerebral microbleeds by susceptibility-weighted imaging in Alzheimer’s disease patients: A neuroimaging biomarker of the disease

Purpose The objective of this study was to correlate the presence and distribution of cerebral microbleeds in Alzheimer’s disease patients with cerebrospinal fluid biomarkers (amyloid-beta and phosphorylated tau 181 protein levels) and cognitive decline by using susceptibility-weighted imaging magnetic resonance sequences at 1.5 T. Material and methods Fifty-four consecutive Alzheimer’s disease patients underwent brain magnetic resonance imaging at 1.5 T to assess the presence and distribution of cerebral microbleeds on susceptibility-weighted imaging images. The images were analyzed in consensus by two neuroradiologists, each with at least 10 years’ experience. Dementia severity was assessed with the Mini-Mental State Examination score. A multiple regression analysis was performed to assess the associations between the number and location of cerebral microbleed lesions with the age, sex, duration of the disease, cerebrospinal fluid amyloid-beta and phosphorylated tau 181 protein levels, and cognitive functions. Results A total of 296 microbleeds were observed in 54 patients; 38 patients (70.4%) had lobar distribution, 13 patients (24.1%) had non-lobar distribution, and the remaining three patients (5.6%) had mixed distribution, demonstrating that Alzheimer’s disease patients present mainly a lobar distribution of cerebral microbleeds. The age and the duration of the disease were correlated with the number of lobar cerebral microbleeds (P < 0.001). Cerebrospinal fluid amyloid-beta, phosphorylated tau 181 protein levels, and cognitive decline were correlated with the number of lobar cerebral microbleeds in Alzheimer’s disease patients (P < 0.001). Conclusion Lobar distribution of cerebral microbleeds is associated with Alzheimer’s disease and the number of lobar cerebral microbleeds directly correlates with cerebrospinal fluid amyloid-beta and phosphorylated tau 181 protein levels and with the cognitive decline of Alzheimer’s disease patients.

The cheating liver: imaging of focal steatosis and fatty sparing

ABSTRACT Focal steatosis and fatty sparing are a frequent finding in liver imaging, and can mimic solid lesions. Liver regional variations in the degree of fat accumulation can be related to vascular anomalies, metabolic disorders, use of certain drugs or coexistence of hepatic masses. CT and MRI are the modalities of choice for the noninvasive diagnosis of hepatic steatosis. Knowledge of CT and MRI appearance of focal steatosis and fatty sparing is crucial for an accurate diagnosis, and to rule-out other pathologic processes. This paper will review the CT and MRI techniques for the diagnosis of hepatic steatosis and the CT and MRI features of common and uncommon causes of focal steatosis and fatty sparing.