Early hepatocellular carcinoma that develops within macroregenerative nodules: growth rate depicted at serial MR imaging

Nodule-in-nodule architecture of hepatocellular carcinomas: enhancement patterns in the hepatobiliary phase and pathological features

PURPOSE

This study aimed to evaluate the enhancement patterns in the hepatobiliary phase (HBP) and pathological features of nodule-in-nodule-type hepatocellular carcinoma (NIN-HCC) patients.

METHODS

In this single-institution retrospective study, 27 consecutive cirrhosis patients with 29 histologically confirmed NIN-HCCs who underwent preoperative examination via Gd-EOB-DTPA-enhanced MRI were enrolled from January 2016 to September 2023. Two blinded radiologists assessed the imaging features of both the inner and outer nodules in NIN-HCCs to reach a consensus on the Liver Imaging Reporting & Data System (LI-RADS) categories of the lesions. Based on the different enhancement patterns of the inner and outer nodules in the HBP, NIN-HCCs were classified into different groups and further divided into different types. Imaging features and LI-RADS categories were subsequently compared among the groups. Pathological findings for NIN-HCCs were also evaluated.

RESULTS

Among 29 NIN-HCCs, all inner nodules showed hypervascularity, with a maximum diameter of 13.2 ± 5.5 mm; 51.7% (15/29) showed "wash-in with washout" enhancement; and 48.3% (14/29) showed "wash-in without washout" enhancement. All outer nodules showed hypovascularity, with a maximum diameter of 25.6 ± 7.3 mm, and 51.9% (14/29) showed a washout appearance on PVP. Among all the lesions, the maximum diameter was 27.5 ± 6.8 mm; 12 (41.4%) lesions were LR-4, and 17 (58.6%) lesions were LR-5. NIN-HCCs were classified into hypointense (62.1%, 18/29) and isointense (37.9%, 11/29) groups based on the signal intensity of the outer nodules in the HBP. In the hypointense group, 2 (6.9%) of the inner nodules were hypointense (type A), 11 (37.9%) were isointense (type B), and 5 (17.2%) were hyperintense (type C) compared to the background hypointense outer nodules. In the isointense group, 9 (31.0%) of the inner nodules were hypointense (type D), 2 (6.9%) were isointense (type E), and no (0%) was hyperintense (type F) compared to the background isointense outer nodules. There were no significant differences in the diameter, dynamic enhancement patterns of the inner or outer nodules, or LI-RADS scores of the lesions between the hypointense group and the isointense group (all P > 0.05). Histologically, the inner nodules of NIN-HCCs were mainly composed of moderately differentiated HCC (75.9% 22/29), whereas the outer nodules consisted of either well-differentiated HCC or high-grade dysplastic nodules (HGDNs).

CONCLUSIONS

NIN-HCCs exhibit specific MRI findings closely associated with their pathological features. The spectrum of HBP enhancement patterns provides valuable insights into the underlying cell biological mechanisms of these lesions. NIN-HCC subtypes may be used as a morphologic marker in the early stage of multistep hepatocarcinogenesis.

Hepatocellular carcinoma tumour volume doubling time: a systematic review and meta-analysis

BACKGROUND

Tumour growth patterns have important implications for surveillance intervals, prognostication and treatment decisions but have not been well described for hepatocellular carcinoma (HCC). The aim of our study was to characterise HCC doubling time and identify correlates for indolent and rapid growth patterns.

METHODS

We performed a systematic literature review of Medline and EMBASE databases from inception to December 2019 and national meeting abstracts from 2010 to 2018. We identified studies reporting HCC tumour growth or tumour volume doubling time (TVDT), without intervening treatment, and abstracted data to calculate TVDT and correlates of growth patterns (rapid defined as TVDT <3 months and indolent as TVDT >9 months). Pooled TVDT was calculated using a random-effects model.

RESULTS

We identified 20 studies, including 1374 HCC lesions in 1334 patients. The pooled TVDT was 4.6 months (95% CI 3.9 to 5.3 months I²=94%), with 35% classified as rapid, 27.4% intermediate and 37.6% indolent growth. In subgroup analysis, studies from Asia reported shorter TVDT than studies elsewhere (4.1 vs 5.8 months). The most consistent correlates of rapid tumour growth included hepatitis B aetiology, smaller tumour size (continuous), alpha fetoprotein doubling time and poor tumour differentiation. Studies were limited by small sample sizes, measurement bias and selection bias.

CONCLUSION

TVDT of HCC is approximately 4-5 months; however, there is heterogeneity in tumour growth patterns, including more aggressive patterns in Asian hepatitis B-predominant populations. Identifying correlates of tumour growth patterns is important to better individualise HCC prognostication and treatment decisions.

Activatable Nanocomposite Probe for Preoperative Location and Intraoperative Navigation for Orthotopic Hepatic Tumor Resection via MSOT and Aggregation-Induced Near-IR-I/II Fluorescence Imaging

The precise location of tumor and completeness of surgical resection are critical to successful tumor surgery; thus, the method capable of preoperatively locating a tumor site and intraoperatively determining tumor margins would be highly ideal. Herein, an activatable nanocomposite probe was developed for preoperatively locating orthotopic hepatic tumor via multispectral optoacoustic tomography imaging and for intraoperative navigation via near-IR-1 (NIR-I) and NIR-II fluorescence imaging. The molecular probe comprises an electronic donor, an acceptor, and a recognition moiety and forms the nanocomposite probe with bovine serum albumin. The probe specifically responds to nitroreductase overexpressed in tumor cells, which transforms the aromatic nitro group into an electron-donating amino group and thus activates the probe. The activated probe with the aggregation-induced emission feature generates strong NIR-I/NIR-II fluorescence and optoacoustic signals for dual-mode imaging. Owing to the in situ response toward nitroreductase in tumor cells in the hepatic region, the probe is found capable of detecting early stage orthotopic liver tumors. Furthermore, with the nanocomposite probe, we can obtain the 3D MSOT images to accurately locate orthotopic liver tumors preoperatively and the NIR-I/NIR-II fluorescence images to provide intraoperative guidance for tumor resection surgery.

State of the art in magnetic resonance imaging of hepatocellular carcinoma

Background

Liver cancer is the sixth most common cancer worldwide and the second leading cause of cancer mortality. Chronic liver disease caused by viral infection, alcohol abuse, or other factors can lead to cirrhosis. Cirrhosis is the most important clinical risk factor for hepatocellular carcinoma (HCC) whereby the normal hepatic architecture is replaced by fibrous septa and a spectrum of nodules ranging from benign regenerative nodules to HCC, each one of them with different imaging features.

Conclusions

Furthermore, advanced techniques including the quantification of hepatic and intralesional fat and iron, magnetic resonance elastography, radiomics, radiogenomics, and positron emission tomography (PET)-MRI are highly promising for the extraction of new imaging biomarkers that reflect the tumor microenvironment and, in the future, may add decision-making value in the management of patients with HCC.

CT-MRI LI-RADS v2017: A Comprehensive Guide for Beginners

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the second leading cause of cancer-related deceases worldwide. Early diagnosis is essential for correct management and improvement of prognosis. Proposed for the first time in 2011 and updated for the last time in 2017, the Liver Imaging-Reporting and Data System (LI-RADS) is a comprehensive system for standardized interpretation and reporting of computed tomography (CT) and magnetic resonance imaging (MRI) liver examinations, endorsed by the American College of Radiology to achieve congruence with HCC diagnostic criteria in at-risk populations. Understanding its algorithm is fundamental to correctly apply LI-RADS in clinical practice. In this pictorial review, we provide a guide for beginners, explaining LI-RADS indications, describing major and ancillary features and eventually elucidating the diagnostic algorithm with the use of some clinical examples.

Nonlinear tumor evolution from dysplastic nodules to hepatocellular carcinoma

Dysplastic nodules are premalignant neoplastic nodules found in explanted livers with cirrhosis. Genetic signatures of premalignant dysplastic nodules (DNs) with concurrent hepatocellular carcinoma (HCC) may provide an insight in the molecular evolution of hepatocellular carcinogenesis. We analyzed four patients with multifocal nodular lesions and cirrhotic background by whole-exome sequencing (WES). The genomic profiles of somatic single nucleotide variations (SNV) and copy number variations (CNV) in DNs were compared to those of HCCs. The number and variant allele frequency of somatic SNVs of DNs and HCCs in each patient was identical along the progression of pathological grade. The somatic SNVs in DNs showed little conservation in HCC. Additionally, CNVs showed no conservation. Phylogenetic analysis based on SNVs and copy number profiles indicated a nonlinear segregation pattern, implying independent development of DNs and HCC in each patient. Thus, somatic mutations in DNs may be developed separately from other malignant nodules in the same liver, suggesting a nonlinear model for hepatocarcinogenesis from DNs to HCC.

Effect of threshold growth as a major feature on LI-RADS categorization

PURPOSE

Liver Imaging Reporting and Data System (LI-RADS) uses major features (arterial phase hyperenhancement [APHE], "washout" [WO], "capsule," diameter, threshold growth [TG]) to codify probability of hepatocellular carcinoma for each observation. This study assessed the effect of removing TG as a major feature on LI-RADS categorization.

MATERIALS AND METHODS

In this HIPAA-compliant, IRB-approved study, all MR and CT clinical reports containing a standardized LI-RADS v2014 template between 4/15-1/17 were retrospectively reviewed for each LR-3, LR-4, and LR-5 reported observation. Two LI-RADS categories were then assigned: one using all LI-RADS major features and one after removing TG as a major feature. The two categories were compared descriptively.

RESULTS

The study included 265 patients (172 [65%] male, mean age 63 [±10] years) with 489 observations (median diameter 14 mm, IQR 10-20 mm), of which 345 (71%) had APHE, 307 (63%) had WO, 86 (18%) had "capsule," and 72 (15%) had TG. Of 86 observations with TG, 47 (65%) were new observations ≥10 mm, 14 (19%) had diameter increase ≥50% in ≤6 months, and 11 (15%) had diameter increase ≥100% in >6 months. Using all major features, 214/489 (44%) observations were LR-3, 129/489 (26%) were LR-4, and 146/489 (30%) were LR-5. After removing TG, 237/489 (48%) were LR-3, 119/489 (24%) were LR-4, and 133 (27%) were LR-5. Removing TG caused a category downgrade for 35/489 (7%, 95% CI 5-10) observations, including 13/146 (9%, 95% CI 3-14) LR-5 observations.

CONCLUSION

9% of LR-5 observations would be downgraded without TG.

Integration of Contrast-enhanced US into a Multimodality Approach to Imaging of Nodules in a Cirrhotic Liver: How I Do It

Accurate characterization of cirrhotic nodules and early diagnosis of hepatocellular carcinoma (HCC) are of vital importance. Currently, computed tomography (CT) and magnetic resonance (MR) imaging are standard modalities for the investigation of new nodules found at surveillance ultrasonography (US). This article describes the successful integration of contrast material-enhanced US into a multimodality approach for diagnosis of HCC and its benefits in this population. The application of contrast-enhanced US immediately following surveillance US allows for prompt dynamic contrast-enhanced evaluation, removing the need for further imaging of benign lesions. Contrast-enhanced US also provides dynamic real-time assessment of tumor vascularity so that contrast enhancement can be identified regardless of its timing or duration, allowing for detection of arterial hypervascularity and portal venous washout. The purely intravascular nature of US contrast agents is valuable as the rapid washout of nonhepatocyte malignancies is highly contributory to their differentiation from HCC. The authors believe contrast-enhanced US provides complementary information to CT and MR imaging in the characterization of nodules in high-risk patients. ^© RSNA, 2017 Online supplemental material is available for this article.

Growth rate of early-stage hepatocellular carcinoma in patients with chronic liver disease

Background/Aims

The goal of this study was to estimate the growth rate of hepatocellular carcinoma (HCC) and identify the host factors that significantly affect this rate.

Methods

Patients with early-stage HCC (n=175) who underwent two or more serial dynamic imaging studies without any anticancer treatment at two tertiary care hospitals in Korea were identified. For each patient, the tumor volume doubling time (TVDT) of HCC was calculated by comparing tumor volumes between serial imaging studies. Clinical and laboratory data were obtained from the medical records of the patients.

Results

The median TVDT was 85.7 days, with a range of 11 to 851.2 days. Multiple linear regression revealed that the initial tumor diameter (a tumor factor) and the etiology of chronic liver disease (a host factor) were significantly associated with the TVDT. The TVDT was shorter when the initial tumor diameter was smaller, and was shorter in HCC related to hepatitis B virus (HBV) infection than in HCC related to hepatitis C virus (HCV) infection (median, 76.8 days vs. 137.2 days; P=0.0234).

Conclusions

The etiology of chronic liver disease is a host factor that may significantly affect the growth rate of early-stage HCC, since HBV-associated HCC grows faster than HCV-associated HCC.

MRI features of hepatocellular carcinoma related to biologic behavior

Imaging studies including magnetic resonance imaging (MRI) play a crucial role in the diagnosis and staging of hepatocellular carcinoma (HCC). Several recent studies reveal a large number of MRI features related to the prognosis of HCC. In this review, we discuss various MRI features of HCC and their implications for the diagnosis and prognosis as imaging biomarkers. As a whole, the favorable MRI findings of HCC are small size, encapsulation, intralesional fat, high apparent diffusion coefficient (ADC) value, and smooth margins or hyperintensity on the hepatobiliary phase of gadoxetic acid-enhanced MRI. Unfavorable findings include large size, multifocality, low ADC value, non-smooth margins or hypointensity on hepatobiliary phase images. MRI findings are potential imaging biomarkers in patients with HCC.

MR characterization of focal liver lesions: pearls and pitfalls

Magnetic resonance (MR) can characterize specific tissue subtypes, thus facilitating focal liver lesion diagnosis. Focal liver lesions that are isointense to hyperintense to liver on T1-weighted images are usually hepatocellular in origin. Chemical shift imaging can narrow the differential diagnosis by detecting the presence of lipid or iron. T2 and heavily T2-weigthed fast spin echo imaging can differentiate solid from nonsolid focal liver lesions. The authors illustrate these MR imaging pearls and the uncommon exceptions (pitfalls). The authors hope that you will find this less traditional contribution to the Magnetic Resonance Clinics of North America helpful in clinical practice.

Magnetic resonance imaging in cirrhosis: what's new?

Cirrhosis is the main risk factor for the development of hepatocellular carcinoma (HCC). The major causative factors of cirrhosis in the United States and Europe are chronic hepatitis C infection and excessive alcohol consumption with nonalcoholic steatohepatitis emerging as another important risk factor. Magnetic resonance imaging is the most sensitive imaging technique for the diagnosis of HCC, and the sensitivity can be further improved with the use of diffusion-weighted imaging and hepatocyte-specific contrast agents. The combination of arterial phase hyperenhancement, venous or delayed phase hypointensity "washout feature," and capsular enhancement are features highly specific for HCC with reported specificities of 96% and higher. When these features are present in a mass in the cirrhotic liver, confirmatory biopsy to establish the diagnosis of HCC is not necessary. Other tumors, such as cholangiocarcinoma, sometimes occur in the cirrhotic at a much lower rate than HCC and can mimic HCC, as do other benign lesions such as perfusion abnormalities. In this article, we discuss the imaging features of cirrhosis and HCC, the role of magnetic resonance imaging in the diagnosis of HCC and other benign and malignant lesions that occur in the cirrhotic liver, and the issue of nonspecific arterially hyperenhancing nodules often seen in cirrhosis.

Magnetic resonance susceptibility-weighted imaging versus other imaging modalities in detecting splenic siderotic lesions

Background

Susceptibility-weighted imaging (SWI) has been proven to be superior to T2*-weighted imaging and also other existing magnetic resonance imaging (MRI) techniques for the detection of iron content and hemorrhage in the brain. The purpose of this study was to compare SWI with T1WI, T2WI and T2*WI in detecting splenic siderotic lesions.

Methodology/Principal Findings

Twenty-two patients with splenic siderotic nodule were imaged with non-contrast MRI T1WI, T2WI, T2*WI and SWI at 3.0 Tesla. Imaging data were independently analyzed by two experienced radiologists. The number of splenic siderotic nodules was counted, and the size (largest diameter) was measured. The conspicuity was calculated as the nodule to background parenchyma intensity ratio. We found that SWI detected a larger average number of splenic siderotic nodules than T1WI, T2WI, or T2*WI (all P<0.05). The average size of the nodules detected by SWI was larger than that of those detected by T1WI, T2WI or T2*WI (all P<0.05). SWI provided superior contrast and visibility for splenic siderotic nodules compared to any other sequence (all P<0.001).

Conclusions

SWI may be a better detection scheme for splenic siderotic nodules than T1WI, T2WI and T2*WI.

Characterizing hepatocellular carcinoma using multi-breath-hold two-dimensional susceptibility-weighted imaging: comparison to conventional liver MRI

AIM

To characterize the imaging manifestations of hepatocellular carcinoma (HCC) using multi-breath-hold two-dimensional susceptibility-weighted imaging (SWI) and compare to conventional liver magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Forty-three patients with histopathologically confirmed HCC underwent conventional liver MRI, multi-breath-hold two-dimensional SWI, and contrast-enhanced CT preoperatively. The T1-weighted imaging (WI), T2WI, and SWI images were evaluated in consensus by two experienced radiologists. The tumour boundaries, blood products in the tumour, venous vessels, and non-tumour liver parenchyma were compared.

RESULTS

SWI demonstrated significantly better tumour boundary detection than T1WI and T2WI imaging (67.4 and 25.6%, respectively). The detection rate for intra-tumoural blood products using SWI was higher than that of T1WI and T2WI (76.7 and 16.3%, respectively). The detection rate for tumour venous vessels using SWI was 72.1%, while none was detected with conventional T1WI and T2WI. The detection rate for siderotic nodules in non-tumour liver parenchyma using SWI was higher than that of conventional T1WI and T2WI (65.1 and 20.9%, respectively).

CONCLUSIONS

SWI can provide more detailed information than conventional liver MRI in evaluation of tumour boundaries, blood products, venous vasculature, and non-tumour liver parenchyma. SWI is a valuable complement to conventional liver MRI.

Improved siderotic nodule detection in cirrhosis with susceptibility-weighted magnetic resonance imaging: a prospective study

Background

Hepatic cirrhosis is a common pathway of progressive liver destruction from multiple causes. Iron uptake can occur within the hepatic parenchyma or within the various nodules that form in a cirrhotic liver, termed siderotic nodules. Siderotic nodule formation has been shown to correlate with inflammatory activity, and while the relationship between siderotic nodule formation and malignancy remains unclear, iron distribution within hepatic nodules has known implications for the detection of hepatocellular carcinoma. We aimed to evaluate the role of abdominal susceptibility-weighted imaging in the detection of siderotic nodules in cirrhotic patients.

Methodology/Principal Findings

Forty-six (46) cirrhotic patients with at least one siderotic nodule detected on previous imaging underwent both computed tomography and magnetic resonance imaging (T1-, T2-, T2*-, and susceptibility-weighted imaging) at 3.0 Tesla. Imaging data was independently analyzed by two radiologists. Siderotic nodule count was determined for each modality and imaging sequence. For each magnetic resonance imaging technique, siderotic nodule conspicuity was assessed on a 3 point scale (1 = weak, 2 = moderate, 3 = strong). More nodules were detected by susceptibility weighted imaging (n = 2935) than any other technique, and significantly more than by T2* weighted imaging (n = 1696, p<0.0001). Lesion conspicuity was also highest with susceptibility-weighted imaging, with all nodules found to be moderate (n = 6) or strong (n = 40); a statistically significant difference (p<0.001).

Conclusions

Susceptibility-weighted imaging had the greatest lesion conspicuity and detected the highest number of siderotic nodules suggesting it is the most sensitive imaging technique to detect siderotic nodules in cirrhotic patients.

Improving detection of siderotic nodules in cirrhotic liver with a multi-breath-hold susceptibility-weighted imaging technique

PURPOSE

To evaluate the role of abdominal susceptibility-weighted imaging (SWI) in the detection of siderotic nodules in cirrhotic liver.

MATERIALS AND METHODS

Forty patients with pathologically identified liver cirrhosis and 40 age/sex-matched normal controls underwent T1-, T2-, T2*-weighted imaging and SWI at 3T. Two radiologists prospectively analyzed all magnetic resonance imaging (MRI) studies. Siderotic nodules detected by each imaging technique were counted for comparison. The conspicuity of siderotic nodules was assessed using a scale from 1 to 3 (1, weak; 2, moderate; 3, prominent).

RESULTS

The number of siderotic nodules detected by SWI (3863) was significantly greater than that of T1-weighted imaging (262, P < 0.001), T2-weighted imaging (842, P < 0.001), and T2*-weighted imaging (2475, P < 0.001). No suspected siderotic nodules were detected in normal controls by any imaging technique.

CONCLUSION

SWI appears to provide the most sensitive method to detect siderotic nodules in cirrhotic liver.

Gadoxetic acid-enhanced MRI findings of early hepatocellular carcinoma as defined by new histologic criteria

PURPOSE

To describe the imaging features of early hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced MRI (Gd-EOB-MRI) in comparison with multidetector computed tomography (MDCT) examinations.

MATERIALS AND METHODS

We analyzed imaging findings of 19 pathologically proven early HCC lesions in 15 patients who underwent both MDCT and Gd-EOB-MRI at 3.0 Tesla (T) units before surgery. MRI included in-phase and out-of-phase T1-weighted dual-echo gradient-recalled-echo sequences, dynamic T1-weighted images before and after bolus injection of gadoxetic acid disodium, fat-saturated T2-weighted fast spin-echo sequences, and T1-weighted hepatobiliary phase images 20 min after contrast injection. Two radiologists retrospectively evaluated the signal intensities and enhancement features on MRI and MDCT.

RESULTS

None of the lesions displayed arterial enhancement and washout on MDCT. On Gd-EOB-MRI, six (32%) lesions showed T2-hyperintensity, five (26%) lesions showed signal drop on opposed-phase. Three lesions (16%) showed arterial enhancement and washout. Twelve (63%), 13 (68%), and 15 (79%) lesions were hypointense on hepatic venous, equilibrium, and hepatobiliary phase, respectively.

CONCLUSION

Most early HCCs did not show arterial enhancement and washout pattern on both MDCT and Gd-EOB-MRI. Gd-EOB-MRI may provide several ancillary findings for diagnosis of early HCC such as decreased hepatobiliary uptake, T2 hyperintensity and signal drop in opposed phase.

MR imaging of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy typically associated with chronic liver disease and is a leading cause of mortality among these patients. Prognosis is improved when detected early. MRI is the best imaging examination for accurate diagnosis. Although arterial enhancement with delayed washout, increased T2-weighted signal intensity, delayed capsular enhancement, restricted diffusion, and tumor thrombus are typical features, not all lesions demonstrate these findings. The radiologist must be familiar with these typical imaging characteristics, and less common appearances and associated findings of HCC, and must be able to differentiate them from those of lesions that mimic HCC. Knowledge of therapeutic options and how those are related to imaging findings is imperative to assist clinicians in managing these patients.

Changes in tumor vascularity precede microbubble contrast accumulation deficit in the process of dedifferentiation of hepatocellular carcinoma

PURPOSE

To elucidate the changes in tumor vascularity and microbubble accumulation on contrast-enhanced sonograms, in relation to the dedifferentiation of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This prospective study enrolled 10 patients with histologically proven HCC (14.4-39.0mm, 26.1+/-7.4) showing nodule-in-nodule appearance upon contrast-enhanced computed tomography. Contrast-enhanced ultrasound was performed by harmonic imaging under a low mechanical index (0.22-0.25) during the vascular phase (agent injection to 1 min) and late phase (15 min) following the injection of Sonazoid (0.0075 ml/kg). Contrast enhancement in the inner and outer nodules was assessed in comparison with that in adjacent liver parenchyma as hyper-, iso-, or hypo-enhanced.

RESULTS

Vascular-phase enhancement of all 10 inner nodules was hyper-enhanced, and that of outer nodules was hyper-enhanced in 3, iso-enhanced in 2, and hypo-enhanced in 5. Late-phase enhancement of inner nodules was hypo-enhanced in 8 and iso-enhanced in 2. Furthermore, late-phase enhancement of outer nodules was iso-enhanced in the 7 lesions that showed iso- or hypo-enhancement in the vascular phase, and hypo-enhanced in the 3 with hyper-enhancement in the vascular phase. Late-phase hypo-enhancement was significantly more frequent in the nodules showing early-phase hyper-enhancement (11/13) than in the nodules showing early-phase iso- or hypo-enhancement (0/7) in both the inner and outer nodules.

CONCLUSION

Dedifferentiation of HCC may be accompanied by changes in tumor vascularity prior to a reduction in microbubble accumulation. Observation of the vascular phase may be more useful than late-phase imaging for the early recognition of HCC dedifferentiation when using contrast-enhanced ultrasound with Sonazoid.

Prostate cancer: sextant localization at MR imaging and MR spectroscopic imaging before prostatectomy--results of ACRIN prospective multi-institutional clinicopathologic study

PURPOSE

To determine the incremental benefit of combined endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging, as compared with endorectal MR imaging alone, for sextant localization of peripheral zone (PZ) prostate cancer.

MATERIALS AND METHODS

This prospective multicenter study, conducted by the American College of Radiology Imaging Network (ACRIN) from February 2004 to June 2005, was institutional review board approved and HIPAA compliant. Research associates were required to follow consent guidelines approved by the Office for Human Research Protection and established by the institutional review boards. One hundred thirty-four patients with biopsy-proved prostate adenocarcinoma and scheduled to undergo radical prostatectomy were recruited at seven institutions. T1-weighted, T2-weighted, and spectroscopic MR sequences were performed at 1.5 T by using a pelvic phased-array coil in combination with an endorectal coil. Eight readers independently rated the likelihood of the presence of PZ cancer in each sextant by using a five-point scale-first on MR images alone and later on combined MR-MR spectroscopic images. Areas under the receiver operating characteristic curve (AUCs) were calculated with sextant as the unit of analysis. The presence or absence of cancer at centralized histopathologic evaluation of prostate specimens was the reference standard. Reader-specific receiver operating characteristic curves for values obtained with MR imaging alone and with combined MR imaging-MR spectroscopic imaging were developed. The AUCs were estimated by using Mann-Whitney statistics and appropriate 95% confidence intervals.

RESULTS

Complete data were available for 110 patients (mean age, 58 years; range, 45-72 years). MR imaging alone and combined MR imaging-MR spectroscopic imaging had similar accuracy in PZ cancer localization (AUC, 0.60 vs 0.58, respectively; P > .05). AUCs for individual readers were 0.57-0.63 for MR imaging alone and 0.54-0.61 for combined MR imaging-MR spectroscopic imaging.

CONCLUSION

In patients who undergo radical prostatectomy, the accuracy of combined 1.5-T endorectal MR imaging-MR spectroscopic imaging for sextant localization of PZ prostate cancer is equal to that of MR imaging alone.

Putative roles of hepatitis B x antigen in the pathogenesis of chronic liver disease

Under most circumstances, hepatitis B virus (HBV) is noncytopathic. However, hepatocellular regeneration that accompanies each bout of hepatitis appears to be associated with increased integration of HBV DNA fragments expressing the virus encoded hepatitis B x antigen (HBxAg). Intrahepatic HBxAg staining correlates with the intensity and progression of chronic liver disease (CLD), and additional work has shown that HBxAg blocks immune mediated killing by Fas and by tumor necrosis factor alpha (TNFalpha). This is not only associated with the blockage of caspase activities by HBxAg, but also by the constitutive stimulation of hepatoprotective pathways, such as nuclear factor kappa B (NF-kappaB), phosphoinositol 3-kinase (PI3K), and beta-catenin (beta-catenin). HBxAg also appears to promote fibrogenesis, by stimulating the production of fibronectin. HBxAg also stimulates the production and activity of transforming growth factor beta1 (TGFbeta1) by several mechanisms, thereby promoting the profibrogenic and tumorigenic properties of this important cytokine. In addition, HBxAg appears to remodel the extracellular matrix (ECM) by altering the expression of several matrix metalloproteinases (MMPs), which may promote tumor metastasis. Hence, HBxAg appears to promote chronic infection by preventing immune mediated apoptosis of infected hepatocytes, by promoting the establishment and persistence of fibrosis and cirrhosis preceding the development of HCC, and by promoting the remodeling of EMC during tumor progression.

Pretreatment endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging features of prostate cancer as predictors of response to external beam radiotherapy

PURPOSE

To evaluate whether pretreatment combined endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) findings are predictive of outcome in patients who undergo external beam radiotherapy for prostate cancer.

METHODS AND MATERIALS

We retrospectively identified 67 men with biopsy-proven prostate cancer who underwent combined endorectal MRI and MRSI at our institution between January 1998 and October 2003 before whole-pelvis external beam radiotherapy. A single reader recorded tumor presence, stage, and metabolic abnormality at combined MRI and MRSI. Kaplan-Meier survival and Cox univariate and multivariate analyses explored the relationship between clinical and imaging variables and outcome, using biochemical or metastatic failure as endpoints.

RESULTS

After a mean follow-up of 44 months (range, 3-96), 6 patients developed both metastatic and biochemical failure, with an additional 13 patients developing biochemical failure alone. Multivariate Cox analysis demonstrated that the only independent predictor of biochemical failure was the volume of malignant metabolism on MRSI (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.29-2.06; p < 0.0001). The two independent predictors of metastatic failure were MRI tumor size (HR 1.34, 95% CI 1.03-1.73; p = 0.028) and the finding of seminal vesicle invasion on MRI (HR 28.05, 95% CI 3.96-198.67; p = 0.0008).

CONCLUSIONS

In multivariate analysis, MRI and MRSI findings before EBRT in patients with prostate cancer are more accurate independent predictors of outcome than clinical variables, and in particular, the findings of seminal vesicle invasion and extensive tumor predict a worse prognosis.

MR imaging of hepatocellular carcinoma: relationship between lesion size and imaging findings, including signal intensity and dynamic enhancement patterns

PURPOSE

To assess the relationship between lesion size and MR imaging findings of pathologically-proven hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

In a retrospective, single-center study, 37 consecutive patients were identified between 1999 and 2005 that underwent preoperative MRI and surgical resection of HCC. A total of 47 lesions (mean size = 6.85 cm, range = 1-25 cm) were assessed for signal intensity (SI), enhancement patterns, and secondary morphologic features. Interobserver rating, percentage enhancement, and contrast-to-noise-ratio (CNR) were determined. Lesions were assessed for combinations of typical MRI features. Regression analysis was used to assess relations between MRI findings and tumor size.

RESULTS

On fat-suppressed T2-weighted (T2w) fast-spin-echo, smaller lesions had lower SI compared to larger lesions (P < 0.05). In the arterial phase, smaller lesions showed significantly higher percentage enhancement compared to larger lesions (P < 0.05). In the delayed phase, smaller lesions showed less pronounced washout (P < 0.05). Heterogeneity of the lesions, including fatty infiltration, internal nodules, or mosaic pattern, was observed significantly more frequently in larger lesions (P < 0.001). The classic combination of high T2w signal, strong arterial enhancement, and delayed phase washout was present in 23 of 44 lesions (52%).

CONCLUSION

Smaller HCC often showed lower SI on T2w, more intense arterial enhancement, and less pronounced delayed washout compared to larger HCC.

CT Imaging of early hepatocellular carcinoma and the natural outcome of hypoattenuating nodular lesions in chronic liver disease

BACKGROUND

The Liver Cancer Study Group of Japan has designated early hepatocellular carcinoma (HCC) a clinically early-stage HCC corresponding to a high-grade dysplastic nodule as proposed by the International Working Party.

METHODS

The majority of resected early HCCs were demonstrated as having hypo- or isoattenuation in the arterial and delayed phases of dynamic CT.

RESULTS

Only 5% of early HCCs were hyperattenuated on dynamic CT, whereas 94% of advanced small HCC were hyperattenuated. CT arterial portography (CTAP) showed that 66% of early HCCs were hypo- and 34% were isoattenuated. CT hepatic arteriography (CTHA) demonstrated that 55% of them were hypo-, 30% were iso- and the remaining 15% were hyperattenuated.

CONCLUSIONS

These findings suggest that most early HCCs receive equal or decreased blood supply from both portal and arterial blood flow compared with surrounding hepatic parenchyma. In contrast, 97% of small advanced HCCs were hypoattenuated on CTAP, and 93% were hyperattenuated on CTHA. For nodule-in-nodule type HCC, the central portion of the lesion was hyperattenuating and the peripheral portion was hypoattenuating in the arterial phase of dynamic CT, and both areas became hypoattenuated in the delayed phase. Sixty hypoattenuating nodular lesions in chronic liver disease were followed periodically with helical CT. Thirty-six (60%) of them developed to the hyperattenuating type (attenuation conversion), 21 were unchanged, and 3 disappeared spontaneously. The hyper-in-hypo-attenuating lesions showed rapid progression to entirely enhanced lesions, i.e. overt HCC. Dynamic CT is recommended as one of the low-invasive imaging modalities to follow the hypoattenuating nodules and to determine the optimal treatment with careful attention being given to intratumoral attenuation conversion.

Hepatocellular carcinoma with indeterminate or false-negative findings at initial MR imaging: effect on eligibility for curative treatment initial observations

PURPOSE

To retrospectively evaluate the effect of indeterminate or false-negative findings at magnetic resonance (MR) imaging on eligibility for curative treatment of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This HIPAA-compliant retrospective study was approved by the institutional review board; the need for informed consent was waived. Of 166 patients with cirrhosis in whom HCC was detected with MR imaging, 21 (13 men, eight women; mean age, 60 years) had 33 proved HCCs that were not detected on previous MR images obtained 6-24 months earlier. MR imaging included T1-weighted, T2-weighted, and dynamic contrast material-enhanced T1-weighted imaging. Serial MR images and treatment records were reviewed to evaluate nodule growth and the effect of delayed diagnosis on treatment eligibility.

RESULTS

Of 33 HCCs in 21 patients, 24 corresponding nodules (73%) were described on previous MR images as benign or indeterminate. Five additional nodules were visible at retrospective evaluation, but only on arterial phase images. The diameters of these 29 visible but indeterminate nodules were initially 0.6-1.9 cm (mean, 1.1 cm) and increased to 0.9-4.5 cm (mean, 1.9 cm) at HCC diagnosis (mean follow-up, 378 days). The mean doubling time was 856 days for diameter and 285 days for volume. All nine HCCs with a delayed diagnosis of less than 1 year were smaller than 3 cm at diagnosis, and the patients had undergone liver transplantation (n=3) or technically successful ablation or embolization (n=6). All 10 subcentimeter indeterminate nodules were smaller than 2 cm at HCC diagnosis, and none progressed to untreatable HCC.

CONCLUSION

Indeterminate nodules smaller than 2 cm did not become untreatable HCC with delayed HCC diagnosis of 6-12 months.

Stepwise carcinogenesis of hepatocellular carcinoma in the cirrhotic liver: demonstration on serial MR imaging

PURPOSE

To demonstrate imaging findings of stepwise carcinogenesis of hepatocellular carcinoma (HCC) in cirrhosis at serial state-of-the-art MR imaging exams.

MATERIALS AND METHODS

In a retrospective search of the hospital archives, three patients were identified in which developing HCC was observed in serial MR examinations, with histopathology or alpha-fetoprotein (AFP) correlation. Image findings were assessed for signal intensity of the lesions at multiple sequences, including dynamic gadolinium-enhanced imaging.

RESULTS

Initial findings in patient A showed a small nodule with fatty infiltration that developed in HCC in follow-up MRI, comprised of low-grade dysplastic nodule (DN; DN I), high-grade DN (DN II), and eventually classic HCC. In patient B, increased signal intensity on T2-weighted images in a single DN among numerous regenerative nodules was the only initial sign. Follow up MRI showed further increase in signal intensity and increased neovascularity, which suggested focal HCC in a DN II. Patient C demonstrated gradually increasing neovascularity as only initial sign, with development of classic HCC over time.

CONCLUSION

MR imaging provides insight in various pathways of stepwise carcinogenesis of developing HCC in cirrhosis. This may further explain the genetic heterogeneity, and may facilitate early detection and better selection of patients for follow-up.

Newly Developed Hepatocellular Carcinoma (HCC) in Chronic Liver Disease

PURPOSE

The purpose of this work was to describe the initial magnetic resonance (MR) imaging findings obtained before an imaging diagnosis of overt hepatocellular carcinoma (HCC) in the chronically damaged liver.

METHODS

One hundred fifty-two newly diagnosed HCCs diagnosed by dynamic computed tomography (n = 111) or by MR imaging (n = 41), in addition to digital subtraction hepatic arteriography, in 96 patients were subjected to analysis of their MR imaging features within the previous 2 years.

RESULTS

Ninety-seven (64%) HCC cases showed no focal lesions distinguishable from background hepatic parenchyma in MR images taken before the indication of typical HCC. The remaining 55 (36%) lesions were readily identified in earlier images and were categorized into 3 groups: nonhypervascular lesions (category I, n = 6), lesions with partially hypervascular foci of "nodule-within-nodule" appearance (category II, n = 12), and homogeneously hypervascular and/or T2-weighted hyperintense lesions (category III, n = 37). The size and doubling time of category III lesions (0.7 cm, 154 days) were smaller and shorter than those of the other lesions (1.2 cm, 377 days).

CONCLUSIONS

Before the imaging diagnosis of HCCs, the premalignant or early malignant lesions can be found on the prior MR images just in the minority of the lesions in the cirrhotic liver.

CT Evaluation of the Progression of Hypoattenuating Nodular Lesions in Virus-Related Chronic Liver Disease

OBJECTIVE

The purpose of this study was to clarify the natural outcomes of hypoattenuating nodular lesions in patients with virus-related chronic liver disease depicted on dynamic CT.

MATERIALS AND METHODS

Sixty lesions (mean size, 1.3 cm) exhibiting hypoattenuation or isoattenuation in the arterial and delayed phases of dynamic CT were retrospectively evaluated with additional CT (mean, six examinations) for a mean period of 838 days. The primary end point was emergence of hyperattenuating areas within hypoattenuating lesions, a phenomenon called attenuation conversion. Cumulative attenuation conversion rates suggesting rates of malignant transformation were calculated with the Kaplan-Meier method, and factors affecting attenuation conversion rate were analyzed with the Cox proportional hazard model.

RESULTS

Thirty-six (60%) of 60 hypoattenuating lesions developed to hyperattenuating lesions, 21 were unchanged, and three disappeared spontaneously. The 36 lesions that became hyperattenuating were divided into two subgroups according to lesion enhancement pattern: hyper-in-hypoattenuating (n = 25) and entirely hyperattenuating (n = 11). The cumulative attenuation conversion rates for the 60 hypoattenuating lesions were 15.8%, 44.3%, and 58.7% at 1, 2, and 3 years. The hyper-in-hypoattenuating lesions showed more rapid progression to entirely enhanced lesions. Positive results for hepatitis C viral antibody (p = 0.028) and initial lesion size (p = 0.007) showed a positive correlation with attenuation conversion rate.

CONCLUSION

Hypoattenuating hepatic nodular lesions in chronic liver disease depicted on dynamic CT have high malignant potential and should be followed with special attention to conversion from hypoattenuation to hyperattenuation to determine the optimal timing of treatment.

Magnetic Resonance Imaging Appearance of Well-differentiated Hepatocellular Carcinoma

OBJECTIVE

To investigate the magnetic resonance imaging (MRI) features of well-differentiated hepatocellular carcinoma (HCC).

METHODS

We reviewed the MRI of 32 patients with 33 pathologically confirmed well-differentiated HCC. The MRI protocol included T2-weighted imaging with and without fat saturation, dual-phase T1-weighted imaging, and gadolinium-enhanced dynamic study. The signal intensity of each lesion was categorized as hyperintense, isointense, and hypointense with reference to the surrounding liver parenchyma.

RESULTS

Thirty-one (93.9%) of 33 well-differentiated HCC were demonstrated on the MRI. The remaining 2 were isointense in all magnetic resonance sequences and, therefore, could not be identified. Most of them were hyperintense (n = 15 [45.4%]) or isointense (n = 16 [48.5%]) on T1-weighted imaging, and hyperintense (n = 12 [36.4%]) or isointense (n = 17 [51.5%]) on T2-weighted imaging. On the dynamic study, 17 lesions (51.5%) were enhanced.

CONCLUSIONS

MRI may identify most well-differentiated HCC; however, the imaging appearance is diverse. Biopsy should be performed if magnetic resonance study is inconclusive.

Imaging well-differentiated hepatocellular carcinoma with dynamic triple-phase helical computed tomography

To investigate the imaging appearance of well-differentiated hepatocellular carcinoma (HCC) on dynamic CT, a total of 38 histopathologically proven well-differentiated HCC were included in a retrospective study. We reviewed the contrast-enhanced dynamic CT of all 38 tumours for attenuation of each tumour in unenhanced scan, arterial-dominant and delayed portal venous phases. Our results showed that dynamic CT identified 26 (68.4%) out of the 38 lesions. The remaining 12 lesions were isodense compared with surrounding liver parenchyma in each dynamic CT phase. There was no statistically significant difference between the mean size of tumours detected by dynamic CT and that of tumours not detected by dynamic CT (p = 0.1). Of a total of 38 tumours, most were isodense (n = 19) or hypodense (n = 16) in unenhanced scan, mostly hyperdense (n = 18) or isodense (n = 15) in arterial-dominant phase and mostly isodense (n = 22) or hypodense (n = 15) in delayed portal venous phase. Enhancement of tumour was observed in 19 (50.0%) of 38 lesions. In conclusion, the ability of dynamic CT to detect well-differentiated HCC is poor, and negative CT findings cannot exclude the presence of well-differentiated HCC, especially if there is well-grounded clinical suspicion for HCC.

Hepatocellular carcinoma: conventional MRI findings including gadolinium-enhanced dynamic imaging

A great variety of MR pulse sequences for hepatocellular carcinomas (HCCs) are now available. In this article, we reviewed the current MR imaging techniques that are routinely used for hepatic imaging, and described the optimization of these sequences as well as the utility and characteristics of each sequence for the accurate diagnosis of HCCs. Then, we reviewed various MR imaging findings of advanced and early HCCs with emphasis on signal intensity and hemodynamic patterns. Finally, we described the value of multi-arterial-phase contrast-enhanced dynamic MR imaging of the whole liver with excellent temporal resolution for evaluating transitional hemodynamics of hepatic lesions during the six arterial phases.

Hepatocellular carcinoma in the cirrhotic liver with helical CT and MRI: imaging spectrum and pitfalls of cirrhosis-related nodules

OBJECTIVE

This article reviews the imaging spectrum of cirrhosis-related nodules on CT and MRI and differentiates between hepatocellular carcinoma (HCC) and common focal lesions that can simulate HCC in the cirrhotic liver.

CONCLUSION

Knowledge of cirrhotic nodules and focal lesions and how they mimic HCC will improve the diagnosis and characterization of focal lesions in cirrhotic liver on CT and MRI.

Growth rate of hepatocellular carcinoma: evaluation with serial computed tomography or magnetic resonance imaging

OBJECTIVE

To evaluate the growth rate of untreated hepatocellular carcinoma (HCC) by calculating tumor volume doubling time (TVDT) on serial computed tomography (CT) or magnetic resonance imaging (MRI) and to predict TVDT based on initial tumor size.

METHODS

Sixteen untreated HCCs in 11 patients with cirrhosis who underwent serial CT or MRI at our institution were retrospectively identified. Two independent readers recorded bidimensional measurements for all tumors, which were used to determine tumor volume (TV). Growth rate was expressed as TVDT. A mathematic model was used to predict TVDT based on baseline tumor size.

RESULTS

Mean baseline and follow-up TVs were 10.5 cm3 (range: 0.7-243.6 cm3) and 22.0 cm3 (range: 2.5-870.8 cm3), respectively. Mean duration of follow-up was 176 days (range: 76-472 days). Mean TVDT was 127 days (95% confidence interval: 80, 203; range: 17.5-541.4 days). Expected TVDT could be expressed as TVDT = 114 x (baseline volume)0.14 (P < 0.002).

CONCLUSION

The results of this study suggest a preferred interval follow-up of approximately 4.5 months (127 days) for HCC screening. Small HCCs show a tendency toward faster growth and may require shorter follow-up to demonstrate progression.

Diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is responsible for a large proportion of cancer deaths worldwide. HCC is frequently diagnosed after the development of clinical deterioration at which time survival is measured in months. Long-term survival requires detection of small tumors, often present in asymptomatic individuals, which may be more amenable to invasive therapeutic options. Surveillance of high-risk individuals for HCC is commonly performed using the serum marker alpha-fetoprotein (AFP) often in combination with ultrasonography. Various other serologic markers are currently being tested to help improve surveillance accuracy. Diagnosis of HCC often requires more sophisticated imaging modalities such as CT scan and MRI, which have multiphasic contrast enhancement capabilities. Serum AFP used alone can be helpful if levels are markedly elevated, which occurs in fewer than half of cases at time of diagnosis. Confirmation by liver biopsy can be performed under circumstances when the diagnosis of HCC remains unclear.

Nodule-in-nodule appearance of hepatocellular carcinomas: comparison of gadolinium-enhanced and ferumoxides-enhanced magnetic resonance imaging

PURPOSE

To perform comparison of gadolinium-enhanced and ferumoxides-enhanced magnetic resonance imaging (MRI) in the detection of nodule-in-nodule appearance of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

During a recent 45-month period, we had eight patients (five men and three women; age range, 63-84 years; mean, 71 years) with HCCs with nodule-in-nodule appearance who underwent gadolinium-enhanced MRI, ferumoxides-enhanced MRI, and computed tomography during arterial portography (CTAP) and computed tomography during hepatic arteriography (CTHA), combined and separately, within an interval of two weeks. Two blinded radiologists in consensus retrospectively evaluated three sets of sequences: unenhanced T1- and T2-weighted MR, gadolinium-enhanced MR, and ferumoxides-enhanced MR images in random order of patients and imaging sequences. The depiction degree of nodule-in-nodule appearance of HCC was evaluated in a semiquantitative fashion. The sensitivities of unenhanced T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images were compared with McNemar's test.

RESULTS

The eight HCCs with nodule-in-nodule appearance ranged in size from 16-26 mm (mean, 20.0 +/- 4.0 mm), and there existed nine internal HCC foci ranging in size from 5-14 mm (mean, 7.9 +/- 3.5 mm). On gadolinium-enhanced MR images, the nodule-in-nodule appearance of HCC was typically seen as hypervascular foci in an iso- or hypovascular area: the depiction degree of nodule-in-nodule appearance was distinct in two lesions, equivocal in three, and absent in three. On ferumoxides-enhanced MR images, it was typically seen as hyperintense foci in a hypointense area: the depiction degree was distinct in four, moderate in one, and absent in three. The sensitivities for detection of nodule-in-nodule appearance were 25%, 25%, and 63% on T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images, respectively, but there was no significant difference in sensitivity.

CONCLUSION

Nodule-in-nodule appearance of HCCs can be seen on ferumoxides-enhanced MR images, in some cases more clearly than on gadolinium-enhanced MR images, particularly when the background nodule shows hyperintensity on precontrast T1-weighted images. Ferumoxides-enhanced MRI may be considered when development of malignant foci is suspected during routine examinations.

Iron-containing nodules of cirrhosis

In the absence of genetic hemochromatosis and systemic hemosiderosis, patients with cirrhosis can accumulate focal iron within regenerative or dysplastic hepatic nodules, commonly referred to as 'siderotic nodules'. Siderotic dysplastic nodules are premalignant lesions while siderotic regenerative nodules are a marker for severe viral or alcoholic cirrhosis. The relationship of hepatic iron deposition to hepatic cirrhosis and neoplasia has not been fully clarified. This article will review the current literature regarding selective iron accumulation in siderotic nodules in chronic liver disease, followed by a discussion of current MR imaging techniques for detection and characterization of these nodules.

MRI features of regenerative and dysplastic nodules in cirrhotic liver

AIM: To study MR features of the regenerative nodule (RN) and dysplastic nodule (DN) in the cirrhotic liver.

METHODS: MRI was performed in 26 cases of suspected cirrhotic liver with RN and DN. Additional enhanced MRI with administration of Gd-DTPA on T1WI was performed in 18 of 26 cases. Meanwhile in 10 of 18 both Gd-DTPA and SPIO (Feridex) enhancement were underwent one day apart. All patients were confirmed by aspiration biopsy or histopathology. MRI was compared to the pathological findings.

RESULTS: In 26 cases, there were 12 cases of regenerative nodules measuring 0.3-1cm in size, and 14 dysplastic nodules including 8 nodules measuring ≥1 cm and <3 cm in size, and 6 nodules measuring ≥3 cm. Their MR appearances were as followings: nodules with <1 cm in size showed isointensity on T₁WI and hypointensity on T₂WI, of which the intensity was as isointense as the surrounding hepatic parenchyma on enhanced MRI with administration of Gd-DTPA or SPIO. In 8 cases with nodules measuring 1-3 cm in size, 5 cases appeared hyperintense on T1WI and hypointense on T₂WI as well as the enhancement as that of nodules with <1 cm in size; the other 3 cases appeared hypointense on T₁WI and hyperintense on T₂WI, and were enhanced after administration of Gd-DTPA but hyperintense on SPIO enhancing MRI, which indicated malignant transformation of dysplastic nodule into hepatocellular carcinoma (HCC) arising from hepatic nodule on histopathology. In 6 cases of nodules measuring >3 cm in size, 2 cases appeared hyperintense compared to the surrounding hepatic parenchyma on T₁, T₂WI and enhanced MRI, one of which was documented "nodule within a nodule" on T₂WI. The 2 cases were demonstrated well-differentiated HCC. The other 4 cases showed hyperintense on T1WI, and hypointense on T₂WI and enhanced MRI. Sometimes, normal vessels were seen to pass through the surface of macroregenerative nodule. Additionally, RN and DN had the same pattern of the time-signal intensity course as the normal surrounding hepatic parenchyma, but malignant transformation of DN appeared fast wash-in and wash-out.

CONCLUSION: RN of cirrhosis has features on MRI that usually allow distinction from HCC but not always from DN. A helpful distinction between HCC and DN is that the latter is almost never hyperintense on T₂WI. Additionally, the followings indicate malignant transformation of DN when DN appears a ring like enhancement after injection of Gd-DTPA, and fast wash-in and wash-out as well as hyperintensity on SPIO enhanced MRI.

Hepatocellular nodules in cirrhosis: focus on diagnostic criteria on liver biopsy. A Western experience

The spectrum of so-called space-occupying small (0.5-2.5 cm) sizable nodules arising in the cirrhotic liver includes a series of hyperplastic (large regenerative), dysplastic (low- and high-grade dysplastic), and malignant hepatocellular (well-differentiated hepatocellular carcinoma, HCC) nodules. Major progress in their classification and understanding was achieved through image analysis techniques and careful histological dissection of explanted native livers. Needless to say, the actual understanding of their natural history is crucial to a proper histological classification. The differential diagnosis of these hepatocellular nodules is difficult, particularly on biopsy specimens of focal liver lesions revealed by ultrasound (US), taken during the follow-up of cirrhotic patients. In this study we attempted to summarize, on the basis of our experience, essential clinicopathological features useful to distinguish the different nodules on needle biopsy. Synoptic tables of differential diagnosis and figures of elementar lesions, which have to be looked for, are provided. Only the continuous integration of clinical features, image analysis information of pathological findings, and follow-up data allows establishing the autonomy of these polymorphic and controversial entities and the boundaries between them.

T2-weighted MR imaging in the assessment of cirrhotic liver

PURPOSE

To assess if T2-weighted magnetic resonance (MR) imaging provides added diagnostic value in combination with dynamic gadolinium-enhanced MR imaging in the detection and characterization of nodular lesions in cirrhotic liver.

MATERIALS AND METHODS

Two readers retrospectively and independently analyzed 54 MR imaging studies in 52 patients with cirrhosis. In session 1, readers reviewed T1-weighted and dynamic gadolinium-enhanced images. In session 2, readers reviewed T1-weighted, dynamic gadolinium-enhanced, and respiratory-triggered T2-weighted fast spin-echo images. Readers identified and characterized all focal lesions by using a scale of 1-4 (1, definitely benign; 4, definitely malignant). Multireader correlated receiver operating characteristic (ROC) analysis was employed to assess radiologist performance in session 2 compared with session 1. The difference in the areas under the ROC curves for the two sessions was tested. In a third session, readers assessed conspicuity of biopsy-proved lesions on T2-weighted MR images by using a scale of 1-3 (1, not seen; 3, well seen) and identified causes of reduced conspicuity.

RESULTS

Two additional benign lesions were detected by each reader in session 2. Fifty-five lesions had pathologic verification, including 32 malignant, three high-grade dysplastic, and 20 benign nodules. There was no significant difference in the area under the ROC curves between the two sessions (P =.48). Thirty-two lesions were inconspicuous on T2-weighted MR images because of parenchymal heterogeneity, breathing artifacts (particularly in patients with ascites), and lesion isointensity with liver parenchyma. T2-weighted MR imaging was useful in the evaluation of cysts and lymph nodes.

CONCLUSION

T2-weighted MR imaging does not provide added diagnostic value in the detection and characterization of focal lesions in cirrhotic liver.