Automated Assessment of T2-Weighted MRI to Differentiate Malignant and Benign Primary Solid Liver Lesions in Noncirrhotic Livers Using Radiomics.

RATIONALE AND OBJECTIVES: Distinguishing malignant from benign liver lesions based on magnetic resonance imaging (MRI) is an important but often challenging task, especially in noncirrhotic livers. We developed and externally validated a radiomics model to quantitatively assess T2-weighted MRI to distinguish the most common malignant and benign primary solid liver lesions in noncirrhotic livers. MATERIALS AND METHODS: Data sets were retrospectively collected from three tertiary referral centers (A, B, and C) between 2002 and 2018. Patients with malignant (hepatocellular carcinoma and intrahepatic cholangiocarcinoma) and benign (hepatocellular adenoma and focal nodular hyperplasia) lesions were included. A radiomics model based on T2-weighted MRI was developed in data set A using a combination of machine learning approaches. The model was internally evaluated on data set A through cross-validation, externally validated on data sets B and C, and compared to visual scoring of two experienced abdominal radiologists on data set C. RESULTS: The overall data set included 486 patients (A: 187, B: 98, and C: 201). The radiomics model had a mean area under the curve (AUC) of 0.78 upon internal validation on data set A and a similar AUC in external validation (B: 0.74 and C: 0.76). In data set C, the two radiologists showed moderate agreement (Cohen's κ: 0.61) and achieved AUCs of 0.86 and 0.82. CONCLUSION: Our T2-weighted MRI radiomics model shows potential for distinguishing malignant from benign primary solid liver lesions. External validation indicated that the model is generalizable despite substantial MRI acquisition protocol differences. Pending further optimization and generalization, this model may aid radiologists in improving the diagnostic workup of patients with liver lesions.

Imaging of Cerebral Venous Thrombosis.

Cerebral venous thrombosis is a rare cause of stroke. Imaging is essential for diagnosis. Although digital subtraction angiography is still considered by many to be the gold standard, it no longer plays a significant role in the diagnosis of cerebral venous thrombosis. MRI, which allows for imaging the parenchyma, vessels and clots, and CT are the reference techniques. CT is useful in case of contraindication to MRI. After presenting the radio-anatomy for MRI, we present the different MRI and CT acquisitions, their pitfalls and their limitations in the diagnosis of cerebral venous thrombosis.

Diagnostic accuracy of Quantitative Colour Doppler Flow imaging in distinguishing Persistent Fetal Vasculature from Retinal Detachment.

PURPOSE: Distinguishing posterior persistent fetal vasculature (PFV) from retinal detachment (RD) may be very challenging clinically and ultrasonographically, as they share common morphological features. However, it is crucial, considering their substantially distinct management and treatment. We aimed to assess the relevance of quantitative colour Doppler flow imaging to distinguish PFV from RD in children. METHODS: This retrospective bi-centre study included 66 children (30 females and 36 males, mean age: 244 ± 257 days) with a clinically suspected diagnosis of RD or posterior PFV. All children underwent systematic and standardized conventional ultrasonography and colour Doppler flow imaging under general anaesthesia with a qualitative and quantitative analysis of the retrolental tissue's vascularization. Peak systolic velocity, end-diastolic velocity and resistive index were recorded for analysis. Whenever available, surgical findings were deemed gold standard for diagnosis. A Mann-Whitney U-test was used to compare quantitative colour Doppler flow imaging data. RESULTS: Peak systolic velocity and end-diastolic velocity were significantly lower in children with PFV versus RD: 2.7 (IQR: 0.5) versus 5.1 (IQR: 2.8), p < 0.001, and 0.0 (IQR: 0.0) versus 2.0 (IQR: 1.2), p < 0.001, respectively. Resistive index was significantly higher in children with PFV versus RD: 1 (IQR: 0) versus 0.6 (IQR: 0.1), p < 0.001. Area under curves (AUCs) were of 0.94, 0.99 and 1, respectively. No differences between PFV and RD were observed on structural ultrasound or qualitative analysis of colour Doppler. CONCLUSION: Quantitative colour Doppler flow imaging has an excellent accuracy in distinguishing PFV from RD in children. It may help to improve management and treatment.

MRI characteristics of intralabyrinthine schwannoma on post-contrast 4 h-delayed 3D-FLAIR imaging.

PURPOSE: The purpose of this study was to describe the MRI characteristics of intralabyrinthine schwannoma (ILS) on post contrast three-dimensional (3D) fluid-attenuation-inversion-recovery (FLAIR) images obtained four hours after intravenous administration of a gadolinium-based contrast agent (4h-3D-FLAIR). MATERIALS AND METHODS: This IRB-approved retrospective multi-center study included patients presenting with typical ILS from January 2016 to October 2020. All medical charts were systematically collected. All MRI examinations, including 4h-3D-FLAIR images, were reviewed by two board-certified neuroradiologists. Main outcome measures were location, signal intensity and associated anomalies of ILS. RESULTS: Twenty-seven out of 8730 patients (0.31%) referred for the investigation of a cochleovestibular disorder had a final diagnosis of ILS. There were 13 men and 14 women with a mean age of 52 ± 17 (SD) years (age range: 20-86 years). The most common clinical presentation was unilateral progressive sensorineural hearing loss (16/27; 59%). All ILS were unilateral and 15 (15/27; 55%) were intracochlear. All ILS presented as a hypointense filling defect within the labyrinth on T2-weighted images that enhanced on post-contrast T1-weighted images. On 4h-3D-FLAIR images, all ILS presented as a hypointense filling defect, associated with diffuse perilymphatic hyperintensity. Two patients (2/27; 7%) presented with ipsilateral endolymphatic hydrops. CONCLUSION: ILS displays consistent features on post-contrast 4h-3D-FLAIR images. ILS should not be confused with endolymphatic hydrops and requires a systematic analysis of the corresponding T2-weighted images.

Radiogenomics of diffuse intrinsic pontine gliomas (DIPGs): correlation of histological and biological characteristics with multimodal MRI features.

OBJECTIVES: The diffuse intrinsic pontine gliomas (DIPGs) are now defined by the type of histone H3 mutated at lysine 27. We aimed to correlate the multimodal MRI features of DIPGs, H3K27M mutant, with their histological and molecular characteristics. METHODS: Twenty-seven treatment-naïve children with histopathologically confirmed DIPG H3K27M mutant were prospectively included. MRI performed prior to biopsy included multi-b-value diffusion-weighted imaging, ASL, and dynamic susceptibility contrast (DSC) perfusion imaging. The ADC and cerebral blood flow (CBF) and blood volume (CBV) were measured at the biopsy site. We assessed quantitative histological data, including microvascular density, nuclear density, and H3K27M-positive nuclear density. Gene expression profiling was also assessed in the samples. We compared imaging and histopathological data according to histone subgroup. We correlated MRI quantitative data with histological data and gene expression. RESULTS: H3.1K27M mutated tumors showed higher ADC values (median 3151 µm2/s vs 1741 µm2/s, p = 0.003), and lower perfusion values (DSC-rCBF median 0.71 vs 1.43, p = 0.002, and DSC-rCBV median 1.00 vs 1.71, p = 0.02) than H3.3K27M ones. They had similar microvascular and nuclear density, but lower H3K27M-positive nuclear density (p = 0.007). The DSC-rCBV was positively correlated to the H3K27M-positive nuclear density (rho = 0.74, p = 0.02). ADC values were not correlated with nuclear density nor perfusion values with microvascular density. The expression of gated channel activity-related genes tended to be inversely correlated with ADC values and positively correlated with DSC perfusion. CONCLUSIONS: H3.1K27M mutated tumors have higher ADC and lower perfusion values than H3.3K27M ones, without direct correlation with microvascular or nuclear density. This may be due to tissular edema possibly related to gated channel activity-related gene expression. KEY POINTS: • H3.1K27M mutant DIPG had higher apparent diffusion coefficient (p = 0.003), lower α (p = 0.048), and lower relative cerebral blood volume (p = 0.02) than H3.3K27M mutant DIPG at their biopsy sites. • Biopsy samples obtained within the tumor's enhancing portion showed higher microvascular density (p = 0.03) than samples obtained outside the tumor's enhancing portion, but similar H3K27M-positive nuclear density (p = 0.84). • Relative cerebral blood volume measured at the biopsy site was significantly correlated with H3K27M-positive nuclear density (rho = 0.74, p = 0.02).

Rapid diffusion-weighted MRI for the investigation of recurrent temporal bone cholesteatoma.

BACKGROUND: Suspected cholesteatoma recurrence is commonly investigated with magnetic resonance imaging (MRI) of the temporal bone. Non-echo planar diffusion-weighted imaging (non-EP DWI) has become the sequence of choice. PURPOSE: To assess the agreement between an MRI protocol incorporating both non-EP DWI and contrast-enhanced sequences, and a shortened protocol without contrast-enhanced sequences in the assessment of suspected cholesteatoma recurrence. MATERIALS AND METHODS: One hundred consecutive MRIs, consisting of T2-weighted, non-EP DWI and pre- and post-contrast T1-weighted sequences, were reviewed by two radiologists at a tertiary referral centre. Agreement between the two protocols was assessment by means of a weighted Cohen kappa coefficient. RESULTS: We found a near perfect agreement between the two protocols (kappa coefficient with linear weighting 0.98; 95% confidence interval 0.95-1.00). There were two cases in which the two protocols were discordant. In both cases, the lesion measured <3 mm and images were degraded by artefact at the bone-air interface. The shortened protocol without post-contrast sequences yielded a 32% reduction in acquisition time. CONCLUSION: When non-EP DWI is available, contrast-enhanced sequences can be omitted in the vast majority of cases without compromising diagnostic accuracy. Contrast-enhanced sequences may provide additional value in equivocal cases with small (<3 mm) lesions or in cases where images are degraded by artefact.

Influence of pretreatment tumor growth rate on objective response of hepatocellular carcinoma treated with transarterial chemoembolization.

BACKGROUND AND AIM: The study aims to assess the influence of pretreatment tumor growth rate (TGR) on modified response evaluation criteria in solid tumors (mRECIST) objective response (OR) after a first session of selective transarterial chemoembolization (TACE) for the treatment of hepatocellular carcinoma (HCC). METHODS: One hundred fifteen patients (101 men [88%], mean 65.1 ± 10.5 years [range 26-87]) with 169 tumors (mean 34.2 ± 29.3 mm [10-160]), undergoing a first session of selective TACE for the treatment of HCC between 2011 and 2016, were included. TGR was calculated as the percentage change in tumor volume per month (%/month) on imaging before treatment. TGR cut-off for prediction of OR was identified by receiver operating characteristic curve analysis. RESULTS: Overall 88/189 (52%) and 46/189 (27%) tumors showed complete response (CR) and partial response (PR) (OR rate 79%), while 32/189 (19%) showed stable disease (SD), and 3/189 (2%) were progressive disease (PD) on computed tomography at 1-month post-TACE. The mean pretreatment TGR was 12.0 ± 15.4 (-3.2-90.4) %/month. TGR of tumors showing CR, PR, SD, and PD was a mean 13.2 ± 16.4%, 12.1 ± 15.1%, 5.3 ± 4.5%, and 44.8 ± 20.4%, respectively (P < 0.001). The three tumors showing PD had TGR values > 20%/month. TGR was significantly higher in tumors with OR (12.8 ± 15.9% vs 5.3 ± 4.5% in SD, P = 0.009). A cut-off value of 6.5%/month had the highest predictive value of OR (AUROC 0.65 ± 0.05, P = 0.009). CONCLUSION: Pretreatment TGR is highly variable in HCC before TACE with a U-shaped distribution for the prediction of tumor response. It provides insight into tumor biology that may be used during pretreatment workup to help stratify patients.

Targeted and non-targeted liver biopsies carry the same risk of complication.

OBJECTIVES: To reappraise the rate of and risk factors for complications of targeted and non-targeted US-guided liver biopsy in a large series. METHODS: We analyzed 2405 liver biopsies performed in 2137 patients (58% males, mean age 54 ± 15 years old) between January 2010 and December 2015. Biopsies were performed for focal liver lesions characterization (targeted) or chronic liver disease assessment (non-targeted). Clinical, laboratory, and technical data were recorded. For targeted biopsies, we also recorded the largest diameter, location, enhancement pattern, and pathology. Advert events were divided into marked symptoms and complications. Those requiring specific treatment (embolization or surgery) were considered as severe. RESULTS: A total of 1283 (53%) targeted and 1122 (47%) non-targeted biopsies were performed. Marked symptoms occurred after 134 biopsies (5.6%) (95 (7.4%) targeted and 39 (3.5%) non-targeted, p < 0.001), the most common being pain (109/134). Complications occurred after 38 biopsies (1.6%) (24 (1.9%) targeted and 14 (1.2%) non-targeted, p = 0.253) and were severe in 13 patients. In univariate analysis, prothrombin time (p = 0.006), serum creatinine level (p < 0.001), largest lesion diameter (p < 0.001), and tumor pathology (p = 0.040) were associated with the occurrence of complications but not platelet count or lesion enhancement pattern. In multivariate analysis, only the largest lesion diameter was retained (OR 1.014 [1.002-1.026], p = 0.018). CONCLUSION: The rate of advert events after US-guided liver biopsy was low, with no difference between targeted and non-targeted biopsies. When focusing on targeted biopsies, the largest lesion diameter but not enhancement pattern appeared as the main risk factor. KEY POINTS: • Targeted and non-targeted liver biopsies are associated with the same observed risk of complication. • Arterial phase hyperenhanced tumors on contrast-enhanced CT or MRI are not associated with a higher risk of complication when compared with non-hyperenhanced ones. • A high serum creatinine level is associated with a higher risk of complication and should motivate strict post-biopsy surveillance.

Iso- or hyperintensity of hepatocellular adenomas on hepatobiliary phase does not always correspond to hepatospecific contrast-agent uptake: importance for tumor subtyping.

PURPOSE: This study was conducted in order to evaluate if iso- or hyperintensity of HCAs on HBP is systematically related to a high uptake of hepatospecific contrast agent, using a quantitative approach. METHODS: This bicentric retrospective study included all patients with histologically confirmed and subtyped HCA from 2009 to 2017 who underwent MRI with HBP after Gd-BOPTA injection and who showed iso- or hyperintensity on HBP. The signal intensity of tumors on pre- and postcontrast images and the presence of hepatic steatosis were noted. Contrast uptake on HBP was quantified using the liver-to-lesion contrast enhancement ratio (LLCER) and compared between HCA subtypes (Wilcoxon signed-rank test). Categorical variables were compared using chi-square tests. RESULTS: Twenty-four HCAs showed iso- or hyperintensity on HBP, specifically 17 inflammatory (IHCAs) and 7 ß-catenin HCAs (BHCAs). Eighteen HCAs (75%) (17 IHCAs and 1 BHCAs) had a LLCER < 0% (median - 13.6%, group 1), of which 94% were hyperintense on precontrast T1-W images, with background hepatic steatosis. Six HCAs (25%) had LLCER ≥ 0% (median 2.9%, group 2), and all were BHCAs. A LLCER ≥ 1.6% was associated with the diagnosis of BHCA with a sensitivity of 86% and a specificity of 100%. CONCLUSION: In conclusion, iso- or hyperintensity of hepatocellular adenomas on HBP does not necessarily correspond to an increased hepatospecific contrast-agent uptake. In IHCA, tumor hyperintensity on precontrast images and the underlying steatosis likely explain such iso- or hyperintensity, which do show reduced HBP contrast-agent uptake. On the other hand, marked contrast uptake can be observed, especially in BHCA. KEY POINTS: • Iso- or hyperintensity on HBP does not necessarily reflect a high uptake of hepatospecific contrast agent. • Discrepancies between qualitative signal intensity and quantitative hepatospecific contrast uptake can be explained in IHCA by a combination of tumor hyperintensity on precontrast images and underlying hepatic steatosis. • In BHCA, iso- or hyperintensity on HBP does actually correspond to a greater contrast uptake than that of the liver, demonstrated by an increased lesion-to-liver contrast enhancement ratio (LLCER).

Hepatocellular Carcinoma: Current Imaging Modalities for Diagnosis and Prognosis.

As opposed to most solid cancers, hepatocellular carcinoma (HCC) does not necessarily require histological confirmation. Noninvasive diagnosis is possible and relies on imaging. In cirrhotic patients, the diagnosis can be obtained in tumors displaying typical features that include non-rim arterial phase hyperenhancement followed by washout during the portal venous and/or delayed phases on CT or MR imaging. This pattern is very specific and, as such, has been endorsed by both Western and Asian diagnostic guidelines and systems. However, its sensitivity is not very high, especially for small lesions. Numerous ancillary features favoring the diagnosis of HCC may be depicted, including appearance after injection of hepatobiliary MR imaging contrast agents. These features increase confidence in diagnosis, but cannot be used as substitutes to liver biopsy. Aside from its diagnostic purpose, imaging also helps to assess tumor biology and patient outcome, by identifying features of local invasiveness. The purpose of this review article is to offer an overview of the role of imaging for the diagnosis and prognostication of HCC.

Hepatocellular carcinoma surveillance: Eastern and Western perspectives.

Eastern and Western guidelines for the management of hepatocellular carcinoma (HCC) are known to significantly differ on many points, because they reflect different diagnostic and therapeutic approaches to this cancer. Importantly, these guidelines are primarily consensus-driven when it comes to surveillance, both in term of the tests used and surveillance program design. The main difference between East and West lies in clinical practice, as several Eastern countries implement coordinated and systematic surveillance programs, while most Western countries rely on individual adherence to surveillance recommendations. This review article presents an overview of the evidence supporting surveillance programs for HCC, with a particular focus on the efficacy, cost-effectiveness, and consequences of this approach for patient survival. Western and Eastern guideline recommendations are discussed.

Low specificity of washout to diagnose hepatocellular carcinoma in nodules showing arterial hyperenhancement in patients with Budd-Chiari syndrome.

BACKGROUND & AIMS: It remains unclear whether the classic imaging criteria for the non-invasive diagnosis of hepatocellular carcinoma (HCC) can be applied to chronic vascular liver diseases, such as Budd-Chiari syndrome (BCS). Herein, we aimed to evaluate the diagnostic value of washout for the discrimination between benign and malignant lesions in patients with BCS. METHODS: This retrospective study included all patients admitted to our institution with a diagnosis of BCS and focal lesions on MRI from 2000 to 2016. MRI images were reviewed by 2 radiologists blinded to the nature of the lesions. Patient and lesion characteristics were recorded, with a focus on washout on portal venous and/or delayed phases. Lesions were compared using Chi-square, Fisher's, Student's t or Mann-Whitney U tests. RESULTS: A total of 49 patients (mean age 35 ±â€¯12 years; 34 women [69%] and 15 men [31%]) with 241 benign lesions and 12 HCC lesions were analyzed. Patients with HCC were significantly older (mean age 44 ±â€¯16 vs. 33 ±â€¯9 years, p = 0.005), with higher alpha-fetoprotein (AFP) levels (median 16 vs. 3 ng/ml, p = 0.007). Washout was depicted in 9/12 (75%) HCC, and 69/241 (29%) benign lesions (p <0.001). A total of 52/143 (36%) lesions ≥1 cm with arterial hyperenhancement showed washout (9 HCC and 43 benign lesions). In this subgroup, the specificity of washout for the diagnosis of HCC was 67%. Adding T1-w hypointensity raised the specificity to 100%. A serum AFP >15 ng/ml was associated with 95% specificity. CONCLUSION: Washout was observed in close to one-third of benign lesions, leading to an unacceptably low specificity for the diagnosis of HCC. The non-invasive diagnostic criteria proposed for cirrhotic patients cannot be extrapolated to patients with BCS. LAY SUMMARY: Washout on MRI is depicted in a significant proportion of benign nodules in patients with Budd-Chiari syndrome (BCS), limiting its value for the differentiation between benign and malignant lesions. Criteria proposed for the non-invasive diagnosis of hepatocellular carcinoma in patients with cirrhosis cannot be extrapolated to patients with BCS. Additional imaging findings and patient characteristics, including alpha-fetoprotein serum level, can help determine the probability of a nodule being HCC in patients with BCS.

Lessons learnt from pathologic imaging correlation in the liver: an historical perspective.

Imaging and pathology can be considered as two sides of the same diagnostic coin. Yet, pathology remains the gold-standard technique for the diagnosis of most diseases. Nevertheless, significant and constant progress in imaging has been made thanks to fruitful rad-path correlations. The aim of this article is to show how much imaging has benefited from pathology and to illustrate the different ways in which imaging has evolved according to different types of pathological references. Imaging of hepatocellular carcinoma shows how image-based knowledge and expertise can be exploited to yield a non-invasive diagnosis approaching that of a fixed, robust pathological reference. Hepatocellular adenomas provide an example of the constant radiological evolutions triggered by changing pathological definitions. Finally, hepatic steatosis illustrates the possibility for imaging to surpass its historical reference, and become a new gold-standard. For these three examples, we have taken a historical approach to demonstrate how rad-path interminglement creates knowledge.

Diagnostic Utility of Computed Tomographic Angiography in Giant-Cell Arteritis.

Background and Purpose- The diagnosis of giant-cell arteritis (GCA) is challenging. Superficial temporal artery biopsy and ultrasound are positive in only 50%. We evaluated computed tomographic angiography (CTA) of the head in GCA. Methods- This case-control study was performed using a prospective GCA registry. Cases presented with stroke symptoms, had a CTA, and were subsequently diagnosed with GCA. Age- and sex-matched controls presented with stroke symptoms, had a CTA, and were not diagnosed with GCA. CTAs were evaluated for the presence of superficial temporal artery abnormalities. Results- Fourteen cases met the inclusion criteria and were matched with 14 controls. Blurred vessel wall margins and perivascular enhancement was found in 10 cases (71.4%) and 2 controls (14.3%). CTA has an accuracy of 78.6%, sensitivity of 71.4%, and a specificity of 85.7% for GCA. Conclusions- CTA detects superficial temporal artery abnormalities in GCA. This may facilitate early diagnosis and prompt implementation of potentially sight-saving and stroke-preventing treatment.

Hepatocellular carcinoma surveillance with ultrasound-cost-effectiveness, high-risk populations, uptake.

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and the second cause of cancer-related deaths worldwide. In most cases, it is diagnosed in patients with identified risk factors, mainly cirrhosis from all causes. These patients are candidates for a surveillance program that, depending on guidelines, involves regular liver ultrasound alone or combined with serum markers. These programs have been shown to improve the oncological outcome by detecting earlier stage tumors and providing patients with potentially curative treatment and improved survival. Yet, the level of evidence supporting these guidelines remains limited. This review article presents an overview of the evidence supporting surveillance programs for hepatocellular carcinoma, in particular the efficacy, cost-effectiveness, and consequences of this approach for patient survival. Western and Eastern guideline recommendations are described and discussed.

Can MRI water apparent diffusion coefficient (ADC) value discriminate between idiopathic normal pressure hydrocephalus, Alzheimer's disease and subcortical vascular dementia?

Numerous similarities in MRI and clinical symptoms exist between Alzheimer's disease (AD), subcortical vascular dementia (sVD) and possible idiopathic normal pressure hydrocephalus (iHPN). The aim of this study is to explore mean apparent coefficient diffusion (ADC) difference between theses diseases in different periventricular and deep white matter areas, as compared to healthy controls. This retrospective study analyzed mean ADC values of 120 patients in normal appearing deep white matter and lenticular nuclei, frontal, caudate nuclei corpus and parietal periventricular and deep white matter areas INPH group showed significantly lower ADC than sVD group in frontal periventricular region (1567.10-6mm2/s vs 1755.10-6mm2/s; P=0.0009) and in parietal deep region (1087.10-6mm2/s vs 1271.10-6mm2/s; P=0.0052), but showed significantly higher ADC in lenticular nuclei ROI (834.10-6mm2/s vs 753.10-6mm2/s; P=0.002). The comparison between iNPH and sVD showed a cut-off value of 1676.10-6mm2/s (sensitivity 0.70, specificity 0.77) in periventricular frontal area. INPH group, in comparison with NA group, showed significantly higher ADC in all ROIs. The iNPH group also showed significantly higher ADC than AD group in all ROIs. AD group showed significantly lower ADC than sVD group in all regions, except in normal appearing lenticular nuclei and caudate nuclei corpus deep ROI. SVD group showed significantly higher ADC than NA in all ROIs, except in normal appearing lenticular nucleus ROI. Different patterns of ADC values can differentiate between AD, sVD and iNPH, even when other MRI sequences appear morphologically similar.

MRI and multiple sclerosis--the evolving role of MRI in the diagnosis and management of MS: the radiologist's perspective.

Magnetic resonance imaging (MRI) plays an integral role in the management of multiple sclerosis (MS), from both diagnostic and therapeutic perspectives. This 2-part review aims to detail the evolving and expanding role of MRI for both radiologists and neurologists. In this article, we discuss the diagnostic criteria for MS relevant to radiologists, as well as its varying imaging manifestations. The role of MRI in therapeutic modification and complications are discussed.

Focal lesions in cirrhosis: Not always HCC.

Even though most hepatocellular carcinomas (HCC) develop in the setting of cirrhosis, numerous other focal liver lesions and pseudolesions may be encountered. The role of the radiologist is therefore to differentiate these lesions from HCC to avoid under- and overdiagnosis. There are several ways of classifying these lesions: those which predate the development of fibrosis and cirrhosis (cystic lesions, hemangioma), those related to or a consequence of cirrhosis (regenerative nodules, dysplastic nodules, focal fibrosis, peribiliary cysts, shunts, or even cholangiocarcinoma), and those related to the underlying cause of chronic liver disease (lymphoma). Finally, some may develop independently (liver metastases). From an imaging point of view, it is important to remember that the imaging features of pre-existing lesions are not dramatically changed by cirrhosis. Differentiating non-HCC from HCC requires not only an understanding of the multi-step process of hepatocarcinogenesis, but also the importance of medical history, and of complimentary imaging modalities, namely computed tomography (CT) and magnetic resonance imaging (MRI). This review article gives an overview of the imaging features of benign and malignant non-HCC focal liver lesions in the setting of cirrhosis, with a focus on CT and MR imaging.