Digital quantification is more precise than traditional semiquantitation of hepatic steatosis: correlation with fibrosis in 220 treatment-naïve patients with chronic hepatitis C

Evaluation of proton density fat fraction (PDFF) obtained from a vendor-neutral MRI sequence and MRQuantif software

OBJECTIVE

To validate the proton density fat fraction (PDFF) obtained by the MRQuantif software from 2D chemical shift encoded MR (CSE-MR) data in comparison with the histological steatosis data.

METHODS

This study, pooling data from 3 prospective studies spread over time between January 2007 and July 2020, analyzed 445 patients who underwent 2D CSE-MR and liver biopsy. MR derived liver iron concentration (MR-LIC) and PDFF was calculated using the MRQuantif software. The histological standard steatosis score (SS) served as reference. In order to get a value more comparable to PDFF, histomorphometry fat fraction (HFF) were centrally determined for 281 patients. Spearman correlation and the Bland and Altman method were used for comparison.

RESULTS

Strong correlations were found between PDFF and SS (rs = 0.84, p < 0.001) or HFF (rs = 0.87, p < 0.001). Spearman's coefficients increased to 0.88 (n = 324) and 0.94 (n = 202) when selecting only the patients without liver iron overload. The Bland and Altman analysis between PDFF and HFF found a mean bias of 5.4% ± 5.7 [95% CI 4.7, 6.1]. The mean bias was 4.7% ± 3.7 [95% CI 4.2, 5.3] and 7.1% ± 8.8 [95% CI 5.2, 9.0] for the patients without and with liver iron overload, respectively.

CONCLUSION

The PDFF obtained by MRQuantif from a 2D CSE-MR sequence is highly correlated with the steatosis score and very close to the fat fraction estimated by histomorphometry. Liver iron overload reduced the performance of steatosis quantification and joint quantification is recommended. This device-independent method can be particularly useful for multicenter studies.

CLINICAL RELEVANCE STATEMENT

The quantification of liver steatosis using a vendor-neutral 2D chemical-shift MR sequence, processed by MRQuantif, is well correlated to steatosis score and histomorphometric fat fraction obtained from biopsy, whatever the magnetic field and the MR device used.

KEY POINTS

• The PDFF measured by MRQuantif from 2D CSE-MR sequence data is highly correlated to hepatic steatosis. • Steatosis quantification performance is reduced in case of significant hepatic iron overload. • This vendor-neutral method may allow consistent estimation of PDFF in multicenter studies.

Hepatic steatosis in patients undergoing resection of colorectal liver metastases: A target for prehabilitation? A narrative review

The prevalence of elevated intra-hepatic fat (IHF) is increasing in the Western world, either alone as hepatic steatosis (HS) or in conjunction with inflammation (steatohepatitis). These changes to the hepatic parenchyma are an independent risk factor for post-operative morbidity following liver resection for colorectal liver metastases (CRLM). As elevated IHF and colorectal malignancy share similar risk factors for development it is unsurprisingly frequent in this cohort. In patients undergoing resection IHF may be elevated due to excess adiposity or its elevation may be induced by neoadjuvant chemotherapy, termed chemotherapy associated steatosis (CAS). Additionally, chemotherapy is implicated in the development of inflammation termed chemotherapy associated steatohepatitis (CASH). Following cessation of chemotherapy, patients awaiting resection have a 4-6 week washout period prior to resection that is a window for prehabilitation prior to surgery. In patients with NAFLD dietary and pharmacological interventions can reduce IHF within this timeframe but this approach to modifying IHF is untested in this population. In this review, the aetiology of CAS and CASH is reviewed with recommendations to identify those at risk. We also focus on the post-chemotherapy washout period, reviewing dietary interventions applied to the metabolic population and suggest this window may be used as an opportunity to optimise IHF with such a regime as part of a pre-operative prehabilitation programme to produce improved patient outcomes.

A Novel Automatic Digital Algorithm that Accurately Quantifies Steatosis in NAFLD on Histopathological Whole-Slide Images

Background

Accurate assessment of hepatic steatosis is a key to grade disease severity in non‐alcoholic fatty liver disease (NAFLD).

Methods

We developed a digital automated quantification of steatosis on whole‐slide images (WSIs) of liver tissue and performed a validation study. Hematoxylin–eosin stained liver tissue slides were digitally scanned, and steatotic areas were manually annotated. We identified thresholds for size and roundness parameters by logistic regression to discriminate steatosis from surrounding liver tissue. The resulting algorithm produces a steatosis proportionate area (SPA; ratio of steatotic area to total tissue area described as percentage). The software can be implemented as a Java plug‐in in FIJI, in which digital WSI can be processed automatically using the Pathomation extension.

Results

We obtained liver tissue specimens from 61 NAFLD patients and 18 controls. The area under the curve of correctly classified steatosis by the algorithm was 0.970 (95% CI 0.968–0.973), P < 0.001. Accuracy of the algorithm was 91.9%, with a classification error of 8.1%. SPA correlated significantly with steatosis grade (Rs = 0.845, CI: 0.749–0.902, P < 0.001) and increased significantly with each individual steatosis grade, except between Grade 2 and 3.

Conclusions

We have developed a novel digital analysis algorithm that accurately quantifies steatosis on WSIs of liver tissue. This algorithm can be incorporated when quantification of steatosis is warranted, such as in clinical trials studying efficacy of new therapeutic interventions in NAFLD. © 2019 The Authors. Cytometry Part B: Clinical Cytometry published by Wiley Periodicals, Inc. on behalf of International Clinical Cytometry Society.

Validation of whole-slide imaging in the primary diagnosis of liver biopsies in a University Hospital

BACKGROUND

Experience in the use of whole slide imaging (WSI) for primary diagnosis is limited and there are no comprehensive reports evaluating this technology in liver biopsy specimens.

AIMS

To determine the accuracy of interpretation of WSI compared with conventional light microscopy (CLM) in the diagnosis of needle liver biopsies.

METHODS

Two experienced liver pathologists blindly analyzed 176 consecutive biopsies from the Pathology Department at the Hospital Clinic of Barcelona. One of the observers performed the initial evaluation with CLM, and the second evaluation with WSI, whereas the second observer performed the first evaluation with WSI and the second with CLM. All slides were digitized in a Ventana iScan HT at 400× and evaluated with the Virtuoso viewer (Roche diagnostics). We used kappa statistics (κ) for two observations.

RESULTS

Intra-observer agreement between WSI and CLM evaluations was almost perfect (96.6%, κ=0.9; 95% confidence interval [95% CI]: 0.9-1 for observer 1, and 90.3%, κ=0.9; 95%CI: 0.8-0.9 for observer 2). Both native and transplantation biopsies showed an almost perfect concordance in the diagnosis.

CONCLUSION

Diagnosis of needle liver biopsy specimens using WSI is accurate. This technology can reliably be introduced in routine diagnosis.

The effect of hepatic steatosis on survival following resection of colorectal liver metastases in patients without preoperative chemotherapy

BACKGROUND

Hepatic steatosis, a common condition associated with insulin resistance and excess body weight, is reported to be associated with an increased risk for perioperative mortality in patients undergoing resection of colorectal liver metastases (CLM), but its impact upon longterm survival is less well documented.

METHODS

The effects of background liver pathology, categorized as 'normal', 'with steatosis' and 'other', on perioperative mortality, overall survival (OS) and cancer-specific survival (CSS) were assessed in patients undergoing resection for CLM according to data maintained in the LiverMetSurvey database. As preoperative chemotherapy may confound the effects of steatosis, patients who had been given preoperative chemotherapy were excluded. Survival analyses included log-rank tests for comparisons, and multivariate Cox models, including well-established prognosticators.

RESULTS

Of 5853 patients who underwent first-time liver resection without preoperative chemotherapy, 1793 (30.6%) had background steatosis. Rates of 90-day perioperative mortality in patients with normal, steatosis and other pathologies were 2.8%, 2.1% and 4.9%, respectively. Steatosis was associated with improved 5-year OS (47.4% versus 43.0%; log rank, P = 0.0017) and CSS (56.1% versus 50.3%; P = 0.002) compared with normal background liver. After adjustments, the survival advantage associated with steatosis remained (hazard ratio = 0.806, 95% confidence interval 0.717-0.905 for CSS).

DISCUSSION

The paradoxical survival advantage observed in patients with steatosis undergoing liver resection for CLM generates a hypothesis that peri-diagnosis of excess body adiposity has a survival protective effect that warrants further research.

Preexisting epithelial diversity in normal human livers: a tissue-tethered cytometric analysis in portal/periportal epithelial cells

Routine light microscopy identifies two distinct epithelial cell populations in normal human livers: hepatocytes and biliary epithelial cells (BECs). Considerable epithelial diversity, however, arises during disease states when a variety of hepatocyte-BEC hybrid cells appear. This has been attributed to activation and differentiation of putative hepatic progenitor cells (HPC) residing in the canals of Hering and/or metaplasia of preexisting mature epithelial cells. A novel analytic approach consisting of multiplex labeling, high-resolution whole-slide imaging (WSI), and automated image analysis was used to determine if more complex epithelial cell phenotypes preexist in normal adult human livers, which might provide an alternative explanation for disease-induced epithelial diversity. "Virtually digested" WSI enabled quantitative cytometric analyses of individual cells displayed in a variety of formats (e.g., scatterplots) while still tethered to the WSI and tissue structure. We employed biomarkers specifically associated with mature epithelial forms (HNF4α for hepatocytes, CK19 and HNF1β for BEC) and explored for the presence of cells with hybrid biomarker phenotypes. The results showed abundant hybrid cells in portal bile duct BEC, canals of Hering, and immediate periportal hepatocytes. These bipotential cells likely serve as a reservoir for the epithelial diversity of ductular reactions, appearance of hepatocytes in bile ducts, and the rapid and fluid transition of BEC to hepatocytes, and vice versa.

CONCLUSION

Novel imaging and computational tools enable increased information extraction from tissue samples and quantify the considerable preexistent hybrid epithelial diversity in normal human liver. This computationally enabled tissue analysis approach offers much broader potential beyond the results presented here.

Wedge and needle liver biopsies show discordant histopathology in morbidly obese patients undergoing Roux-en-Y gastric bypass surgery

Background: Controversy exists over whether or not single-needle liver biopsies are sufficient to compare histological parameters in patients with non-alcoholic fatty liver disease.

Aims: To identify sampling variability, we biopsied four liver specimens per patient, based on biopsy size (needle vs wedge) and location (left vs right lobe), immediately prior to bariatric Roux-en-Y gastric bypass surgery.

Methods: Ten prospectively enrolled, morbidly obese patients underwent 40 laparoscopy-guided biopsies; two needle and two wedge from each of 16 left and 16 right liver lobes. The Kappa coefficient for concordance compared histological parameters from left and right lobe needle- and wedge biopsies. Wedge biopsies were considered our ‘Gold Standard’.

Results: Each patient had two wedge- and two needle liver biopsies. Kappa concordance between all needle and wedge biopsies from right and left lobes showed variability. Wedge- and needle liver biopsies from contralateral lobes had higher concordance with each other, compared to ipsilateral needle/wedge biopsy pairs. Contralateral wedge pairs had higher concordance than contralateral needle/needle pairs. There were no biopsy complications.

Conclusions: Wedge biopsy pairs had the best Kappa concordance but contralateral needle/needle biopsy pairs had good Kappa concordance. There were no complications from the 40 needle- and wedge liver biopsies, confirming the safety of laporoscopic multi-biopsy in both liver lobes.

Frozen section diagnosis in donor liver biopsies: observer variation of semiquantitative and quantitative steatosis assessment

Donor livers are not generally accepted for liver transplantation if intraoperative frozen section histology on wedge biopsies provides evidence for more severe steatosis. In this reliability study, assessment of steatosis in donor liver biopsies by different approaches (frozen sections vs. paraffin sections; macrovesicular steatosis vs. microvesicular steatosis), different observers, and different evaluation methods (conventional microscopy vs. point grid analysis on digital microphotographs) was compared. One hundred twenty consecutive donor liver biopsies were investigated. Intraoperative diagnosis was made on hematoxylin and eosin (H&E)-stained frozen sections. The residual portion of each biopsy was analyzed later on H&E-, diastase-resistant PAS-, and Elastica van Gieson-stained paraffin sections. Microvesicular steatosis and macrovesicular steatosis were classified semiquantitatively into 5 % steps. Additionally, point grid counting was applied on ten digital microphotographs per slide. The values for steatosis revealed a wide range of data between 0 and 70 or 85 % (mean values, 12.0-18.3 %), considering all types of specimens. The results of the two observers were highly correlated for macrovesicular steatosis (r ≥ 0.925) and for microvesicular steatosis (r ≥ 0.880). The values for macrovesicular and microvesicular steatosis, however, showed poor correlation (r ≤ 0.581). The rate of agreement between the two observers ranged between 84.2 and 95.8 % (κ, 0.763-0.937), depending on the threshold setting. For point grid analysis, significantly lower mean values and ranges for both types of steatosis compared to conventional histopathology were found (p < 0.001). Comparing the results of point grid analysis with those of conventional histopathology, a relatively loose correlation was found (r, 0.581-0.779). Intraoperative histology remains a reliable and highly relevant method for the assessment of steatosis in liver donor grafts. It represents one important component in the decision-finding whether or not a donor liver should be accepted and should possibly be combined with results of preoperative computed tomography imaging. Considering our data, macrovesicular and microvesicular steatosis should be analyzed separately due to the limited correlation between them.

Digital imaging in pathology--current applications and challenges

Conventional histopathology is rapidly shifting towards digital integration. Will microscopes (and pathologists) soon be obsolete? Or are we dealing with just another image modality that leaves the core of tissue diagnosis intact? This article provides an overview of current digital pathology applications and research with emphasis on whole slide imaging (WSI). Static or interactive digital pathology work stations already can be used for many purposes, e.g. telepathology expert consultations, frozen section diagnosis in remote areas, cytology screening, quality assurance, diagnostic validations for clinical trials, quantitation of hormone receptor or HER2 studies in breast cancer, or three-dimensional visualization of anatomical structures, among others. Changes of workflow in histology laboratories are beginning to enable digital image acquisition and WSI in a routine setting. WSI plays an increasing role in pathology education, glass slide boxes in medical schools are being replaced by digital slide collections; digital slide seminars and virtual microscopy are used for postgraduate and continuing medical education in pathology. Research and efforts to validate WSI systems for diagnostic settings are ongoing.

The value of pre-operative magnetic resonance spectroscopy in the assessment of steatohepatitis in patients with colorectal liver metastasis

BACKGROUND & AIMS

Neoadjuvant chemotherapy prior to liver surgery for colorectal metastases can cause marked steatosis (≥ 33%) and steatohepatitis defined by non-alcoholic fatty liver disease activity score (NAS) as adverse effects on liver parenchyma. The aim of this study was to evaluate the steatosis level prior to liver resection using proton magnetic resonance spectroscopy ((1)H MRS) and to compare it with digital quantification of steatosis (DQS) and "classical" histopathology.

METHODS

(1)H MRS at 3T evaluated steatosis in 35 patients with colorectal liver metastasis, planned for liver resection. Non-tumorous liver parenchyma samples were obtained after surgery for classical histopathology and DQS utilising automated software for quantification of histopathological slides using image processing.

RESULTS

Classical histopathology defined marked steatosis in nine patients. Histopathology was less reliable than DQS (interclass correlation coefficient - ICC 0.771) or (1)H MRS (ICC 0.722) in steatosis estimation. (1)H MRS showed very similar steatosis levels and high reliability compared to DQS (ICC 0.955). Steatohepatitis was observed in seven patients (NAS ≥ 4) and (1)H MRS was able to predict it with 100% sensitivity and 89% specificity at threshold 10.9%, without knowing lobular inflammation or hepatocyte ballooning. BMI was significantly higher in the groups with marked steatosis and steatohepatitis. Standard blood tests or chemotherapy had no predictive value.

CONCLUSIONS

(1)H MRS is a reliable non-invasive tool for steatosis assessment, and interestingly, it was able to predict steatohepatitis defined by NAS ≥ 4 in patients planned for liver resection of colorectal metastases after neoadjuvant chemotherapy.

A critical analysis of three quantitative methods of assessment of hepatic steatosis in liver biopsies

The issue of adequately quantitatively evaluating hepatic steatosis is still unresolved. Therefore, we compared three methods of quantitative assessment. Two groups of mice (n = 10 each) were fed standard chow (10% fat, SC group) or a high-fat diet (60% fat, HF group) for 16 weeks, and hepatic triglyceride (HT) and liver tissue were then studied. Paraplast-embedded tissues stained by hematoxylin and eosin (H-E) were compared to frozen sections stained by Oil Red-O (ORO). In addition, the volume density of steatosis (Vv[steatosis, liver]) was measured by point counting (P-C, sections H-E or ORO) or by image analysis (I-A, sections ORO). HT was significantly higher in the HF group (104% greater, P = 0.0004) than in the SC group. With P-C and H-E, Vv[steatosis, liver] was 4.80 ± 0.90% in the SC group and 33.50 ± 3.17% in the HF group (600% greater, P < 0.0001). With P-C and ORO, Vv[steatosis, liver] was 4.86 ± 0.89% in the SC group and 25.21 ± 1.27% in the HF group (420% greater, P < 0.0001). With I-A and ORO, Vv[steatosis, liver] was 4.17 ± 0.85% in the SC group and 23.35 ± 1.58% in the HF group (460% greater, P < 0.0001). Correlations between Vv[steatosis, liver] and HT were strong and significant in all methods. In conclusion, all methods were appropriate and reproducible. In P-C and H-E, there is a slight overestimation of steatosis in the HF animals in comparison to frozen sections and ORO; in frozen sections, differences between P-C and I-A are insignificant.

Effect of disease progression on liver apparent diffusion coefficient values in a murine model of NASH at 11.7 Tesla MRI

PURPOSE

To evaluate the apparent diffusion coefficient (ADC) values of liver in a murine model of non-alcoholic steatohepatitis using 11.7 Tesla (T) MRI.

MATERIALS AND METHODS

This animal study was IACUC approved. Seventeen male C57BL/6 mice were divided into control (n = 3) and experimental groups (n = 14) fed a methionine-deficient choline-deficient (MCD) diet to induce steatohepatitis. Livers underwent ex vivo diffusion-weighted MR imaging and ADC maps were calculated. A pathologist determined subjective scores of steatosis, classified from 0 to 3. Digital image analysis was used to determine percentage areas of steatosis. Graphs comparing ADC to subjective and digital image analysis (DIA) determinations of steatosis were plotted.

RESULTS

Subjective assessments of steatosis ranged up to values of 3 and DIA determined areas of steatosis to range up to approximately 16%. ADC values approximated 800 × 10(-6) mm(2) /s (range, 749-811 × 10(-6) mm(2) /s, mean 786 × 10(-6) mm(2) /s) in controls and 500 × 10(-6) mm(2) /s (range, 478-733 × 10(-6) mm(2) /s, mean 625 × 10(-6) mm(2) /s) in experimental mice. Moderate correlation between ADC and subjective scores of steatosis (R = -0.56) was observed. Strong correlation between ADC values and percentage areas of steatosis was between ADC values and percentage areas of steatosis was observed greater (R = -0.81) and very strong correlation was observed with the exclusion of a single outlying data point (R = -0.91).

CONCLUSION

Based on the comparison of ADC values and steatosis determinations by DIA, increasing degrees of steatosis are seen to result in decreased hepatic ADC values.

Comparing morphometric, biochemical, and visual measurements of macrovesicular steatosis of liver

The degree of macrovesicular steatosis is typically evaluated in liver biopsies by visual estimation, which is subject to intraobserver and interobserver variations. Computer morphometry and biochemical measurement may provide more accurate results. Our aim was to develop a morphometry method and compare its results with visual and biochemical measurements. Twenty-six fresh frozen liver specimens were each divided into 4 aliquots. Three aliquots were processed biochemically to extract fat, and the fat content was defined as the weight percentage of fat. One aliquot was fixed in formalin, from which hematoxylin and eosin slides were made and reviewed by 3 pathologists to estimate fat content. Digital images of slides were analyzed by computer morphometry, which defined fat content as the percentage of area occupied by fat droplets. The results showed that individually, each method produced highly precise and reproducible measurements. Compared with each other, they showed very strong correlations (correlation coefficient r = 0.81-0.95). The range of fat content in all 26 specimens was 2.2% to 15% by biochemical, 0.8% to 82.5% by visual, and 0.3% to 19.6% by morphometry method. Visual estimation appeared to have a systematic bias, giving results nearly 4-fold higher than other methods. This may be because visual estimation denotes the fraction of hepatocytes containing fat droplets, instead of the true fraction of fat. Strong correlations between different methods suggest that all 3 are valid methods for measuring steatosis. Computer morphometry is easy to implement and not affected by the bias seen in visual estimation. It may serve as a potential supplemental or alternative method.