Magnetic Resonance Imaging as a Valid Noninvasive Tool for the Assessment of Pancreatic Fibrosis

3D histology reveals that immune response to pancreatic precancers is heterogeneous and depends on global pancreas structure

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer for which few effective therapies exist. Immunotherapies specifically are ineffective in pancreatic cancer, in part due to its unique stromal and immune microenvironment. Pancreatic intraepithelial neoplasia, or PanIN, is the main precursor lesion to PDAC. Recently it was discovered that PanINs are remarkably abundant in the grossly normal pancreas, suggesting that the vast majority will never progress to cancer. Here, through construction of 48 samples of cm3-sized human pancreas tissue, we profiled the immune microenvironment of 1,476 PanINs in 3D and at single-cell resolution to better understand the early evolution of the pancreatic tumor microenvironment and to determine how inflammation may play a role in cancer progression. We found that bulk pancreatic inflammation strongly correlates to PanIN cell fraction. We found that the immune response around PanINs is highly heterogeneous, with distinct immune hotspots and cold spots that appear and disappear in a span of tens of microns. Immune hotspots generally mark locations of higher grade of dysplasia or locations near acinar atrophy. The immune composition at these hotspots is dominated by naïve, cytotoxic, and regulatory T cells, cancer associated fibroblasts, and tumor associated macrophages, with little similarity to the immune composition around less-inflamed PanINs. By mapping FOXP3+ cells in 3D, we found that regulatory T cells are present at higher density in larger PanIN lesions compared to smaller PanINs, suggesting that the early initiation of PanINs may not exhibit an immunosuppressive response. This analysis demonstrates that while PanINs are common in the pancreases of most individuals, inflammation may play a pivotal role, both at the bulk and the microscopic scale, in demarcating regions of significance in cancer progression.

The Signal Intensity Ratio of Pancreas to Spleen in Magnetic Resonance Imaging Can Predict Nonalcoholic Fatty Liver Disease After Pancreaticoduodenectomy

OBJECTIVES

Signal intensity ratio of pancreas to spleen (SI ratio p/s ) on fat-suppressed T1-weighted images of magnetic resonance imaging has been associated with pancreatic exocrine function. We here investigated the predictive value of the SI ratio p/s for the development of nonalcoholic fatty liver disease (NAFLD) after pancreaticoduodenectomy (PD).

MATERIALS AND METHODS

This study comprised 208 patients who underwent PD. NAFLD was defined as a liver-to-spleen attenuation ratio of <0.9 calculated by a computed tomography 1 year after surgery. SI ratio p/s was calculated by dividing the average pancreas SI by the spleen SI. We retrospectively investigated the association of clinical variables including the SI ratio p/s and NAFLD by univariate and multivariate analyses.

RESULTS

NAFLD after 1 year was developed in 27 patients (13%). In multivariate analysis, the SI ratio p/s < 1 ( P < 0.001) was an independent predictor of incidence of NAFLD. The SI ratio p/s < 1 was associated with low amylase level of the pancreatic juice ( P < 0.001) and progressed pancreatic fibrosis ( P = 0.017). According to the receiver operating characteristics curve, the SI ratio p/s had better prognostic ability of NAFLD than the remnant pancreas volume.

CONCLUSIONS

The SI ratio p/s is useful to predict NAFLD development after PD. Moreover, the SI ratio p/s can be a surrogate marker, which represents exocrine function of the pancreas.

Quantitative Magnetic Resonance Imaging for the Pancreas: Current Status

ABSTRACT

Magnetic resonance imaging (MRI) is important for evaluating pancreatic disorders, and anatomical landmarks play a major role in the interpretation of results. Quantitative MRI is an effective diagnostic modality for various pathologic conditions, as it allows the investigation of various physical parameters. Recent advancements in quantitative MRI techniques have significantly improved the accuracy of pancreatic MRI. Consequently, this method has become an essential tool for the diagnosis, treatment, and monitoring of pancreatic diseases. This comprehensive review article presents the currently available evidence on the clinical utility of quantitative MRI of the pancreas.

Radiological parameters to predict pancreatic texture: Current evidence and future perspectives

Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management, thereby minimizing postoperative morbidity. Pancreatic duct diameter can be readily measured by any routine imaging used to diagnose pancreatic disease. However, radiological evaluation of pancreatic texture, an important determinant of pancreatic fistula, has not been widely used to predict the risk of postoperative pancreatic fistula. Qualitative and quantitative assessment of pancreatic fibrosis and fat fraction provides the basis for predicting pancreatic texture. Traditionally computed tomography has been utilized in identifying and characterizing pancreatic lesions and background parenchymal pathologies. With the increasing utilisation of endoscopic ultrasound and magnetic resonance imaging for evaluating pancreatic pathologies, elastography is emerging as a promising tool for predicting pancreatic texture. Also, recent studies have shown that early surgery for chronic pancreatitis is associated with better pain relief and preservation of pancreatic function. Pancreatic texture assessment can allow early diagnosis of chronic pancreatitis, facilitating early intervention. The present review outlines the current evidence in utilizing various imaging modalities for determining the pancreatic texture based on different parameters and image sequences. However, multidisciplinary investigations using strong radiologic-pathologic correlation are needed to standardize and establish the role of these non-invasive diagnostic tools in predicting pancreatic texture.

Fibrosis in Liver and Pancreas: a Review on Pathogenic Significance, Diagnostic Options, and Current Management Strategies

Inflammation is one of the most natural ways of the body's biological response against invading foreign pathogens or injured cells which eventually can lead to a chronic or acute productive response. Fibrosis is an end-stage event associated with an inflammatory response addressed with tissue hardening, discoloration, and most importantly overgrowth of associated tissue. Various organs at different diseased conditions are affected by fibrosis including the liver, pancreas, brain, kidney, and lung. Etiological factors including internal like inflammatory cytokines, growth factors, and oxidative stress and external like alcohol and viruses contribute to the development of fibrosis in both the liver and pancreas. More frequently, these organs are associated with pathogenic progression towards fibrosis from acute and chronic conditions and eventually fail in their functions. The pathogenesis of the organ-fibrotic events mainly depends on the activation of residential stellate cells; these cells help to accumulate collagen in respective organs. Various diagnostic options have been developed recently, and various therapeutic options are in trial to tackle fibrosis. In this review, an overview on fibrosis, the pathogenesis of fibrosis in the liver and pancreas, various diagnostic options developed in recent years, and possible present therapeutic measures to overcome options of fibrosis in the liver and pancreas; thus, restoring the functional status of organs is discussed.

Histological pancreatic findings correlate with computed tomography attenuation and predict postoperative pancreatic fistula following pancreatoduodenectomy

BACKGROUND

Although a soft pancreas is a widely-accepted reliable risk factor for postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD), there is no established preoperative evaluation of pancreatic texture.

METHODS

Two hundred thirty-seven patients who underwent PD with histological pancreatic assessment were retrospectively enrolled. The degree of fibrosis and fatty infiltration was scored histologically as seven grades and five grades, respectively. Computed tomography (CT) attenuation of the pancreas was measured on preoperative unenhanced CT images. Correlations between the CT attenuation of the pancreas and the histological pancreatic findings, and the development of POPF were analyzed.

RESULTS

The fibrosis grade was significantly higher for hard pancreas than for soft pancreas (p < 0.001), whereas the fatty infiltration grade was similar between the two types (p = 0.161). CT attenuation of the pancreas was inversely correlated with both fibrosis grade (Spearman's rank correlation coefficient ([r] = -0.609, p < 0.001) and fatty infiltration grade (r = -0.382, p < 0.001). Multivariate analysis showed that body mass index ≥25 kg/m² (odds ratio [OR]: 5.64, p < 0.001) and fibrosis grade ≤2 (OR: 18.0, p < 0.001) were independent risk factors for clinically significant POPF.

CONCLUSION

Histological pancreatic texture can be evaluated with CT attenuation and might be helpful in preoperatively predicting the development of POPF after PD.

Evaluating the Histopathology of Pancreatic Ductal Adenocarcinoma by Intravoxel Incoherent Motion-Diffusion Weighted Imaging Comparing With Diffusion-Weighted Imaging

Objectives

To explore the differences between intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and diffusion-weighted imaging (DWI) in evaluating the histopathological characters of pancreatic ductal adenocarcinoma (PDAC).

Methods

This retrospective study enrolled 50 patients with PDAC confirmed by pathology from December 2018 to May 2020. All patients underwent DWI and IVIM-DWI before surgeries. Patients were classified into low- and high-fibrosis groups. Apparent diffusion coefficient (ADC), diffusion coefficient (D), false diffusion coefficient (D*), and perfusion fraction (f) were measured by two radiologists, respectively in GE AW 4.7 post-processing station, wherein ADC values were derived by mono-exponential fits and f, D, D* values were derived by biexponential fits. The tumor tissue was stained with Sirius red, CD34, and CK19 to evaluate fibrosis, microvascular density (MVD), and tumor cell density. Furthermore, the correlation between ADC, D, D*, and f values and histopathological results was analyzed.

Results

The D values were lower in the high-fibrosis group than in the low-fibrosis group, while the f values were opposite. Further, no statistically significant differences were detected in ADC and D* values between the high- and low-fibrosis groups. The AUC of D and f values had higher evaluation efficacy in the high- and low-fibrosis groups than ADC values. A significant negative correlation was established between D values, and fibrosis and a significant positive correlation were observed between f values and fibrosis. No statistical difference was detected between DWI/IVIM parameters values and MVD or tumor cell density except for the positive correlation between D* values and tumor cell density.

Conclusions

D and f values derived from the IVIM model had higher sensitivity and diagnostic performance for grading fibrosis in PDAC compared to the conventional DWI model. IVIM-DWI may have the potential as an imaging biomarker for predicting the fibrosis grade of PDAC.

Evaluation of Pancreatic Fibrosis Grading by Multi Parametric Quantitative Magnetic Resonance Imaging

BACKGROUND

Early detection and grading of pancreatic fibrosis (PF) are important and challenging clinical goals.

PURPOSE

To determine main pancreatic duct (MPD) diameter, pancreatic thickness, and grades of PF via magnetic resonance elastography (MRE), T1 mapping, and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), assessing respective diagnostic performances.

STUDY TYPE

Prospective.

SUBJECTS

Histopathologic and imaging records (MRE, T1 mapping, and IVIM-DWI) generated by 144 patients between December 2018 and May 2020 were collected for analysis. Grades of PF were distributed as follows: F0, 82; F1, 22; F2, 22; and F3, 18.

FIELD STRENGTH/SEQUENCE

3 T pancreatic MRI, encompassing MRE, T1 mapping, and IVIM-DWI.

ASSESSMENT

In all patients, T1 relaxation times, pancreatic stiffness values, IVIM-DWI parameters, MPD diameter, and pancreatic thickness were measured.

STATISTICAL TESTS

Receiver operating characteristic (ROC) analysis served to assess imaging parameters useful in diagnosing PF. To identify relations between specific parameters and grades of PF, logistic regression analysis was invoked.

RESULTS

Both pancreatic stiffness (r = 0.754; P < 0.001) and T1 relaxation time (r = 0.433; P < 0.001) correlated significantly with PF (%). To determine PF grades ≥F1, a combined model (area under the curve [AUC] = 0.906) performed significantly better than pancreatic stiffness (AUC = 0.855; P < 0.001) or T1 relaxation time (AUC = 0.754; P < 0.001) alone. For PF grades ≥F2 or grade F3, both the combined model (≥F2: AUC = 0.910; F3: AUC = 0.939) and pancreatic stiffness (≥F2: AUC = 0.906; F3: AUC = 0.929) outperformed T1 relaxation time (≥F2: AUC = 0.768 [P = 0.005 and P = 0.004, respectively]; F3: AUC = 0.816 [both P < 0.005]). All IVIM-DWI parameters generated AUC values <0.700.

DATA CONCLUSION

A combination of MRE and T1 mapping seems promising in diagnosing various grades of PF, particularly at an early stage.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.

Pancreatic atrophy and exocrine insufficiency associate with the presence of diabetes in chronic pancreatitis patients, but additional mediators are operative

OBJECTIVES

Diabetes mellitus is a frequent complication of chronic pancreatitis (CP) and has traditionally been considered to develop as a consequence of pancreatic islet cell loss. However, additional mechanisms may be operative including accumulation of pancreatic fat and fibrosis. We used advanced magnetic resonance imaging (MRI) to study pancreatic morphology and exocrine function in a reference population and in CP patients with and without diabetes.

METHODS

This was a cross-sectional mono centre study. All subjects underwent advanced MRI including assessment of pancreatic ductal parameters (Cambridge classification and main pancreatic duct diameter), parenchymal parameters (DIXON technique and diffusion weighted imaging as proxies for pancreatic fat content and fibrosis, as well as pancreatic volume segmentation). Pancreatic exocrine function was determined as duodenal secretion following secretin stimulation and by the faecal elastase test.

RESULTS

The study included 76 patients with definite CP of whom 23 (30.1%) had diabetes and 23 sex- and age matched healthy volunteers. Compared to their non-diabetic counterparts, diabetic patients were characterised by a low pancreatic volume (20 vs. 36 ml; p = .02) and impaired pancreatic exocrine function (faecal elastase 19 vs. 48 µg/g; p = .008), while no difference between patients with and without diabetes were seen in relation to MRI derived proxies for fibrosis and pancreatic fat accumulation and pancreatic duct parameters. A large proportion of non-diabetic patients (49%) had similar morphological and functional characteristics as patients with diabetes.

CONCLUSION

Pancreatic atrophy and exocrine insufficiency are present in most CP patients with diabetes, but additional mediators seem to be operative in post pancreatitis diabetes mellitus.

Progression of pancreatic morphology in chronic pancreatitis is not associated with changes in quality of life and pain

OBJECTIVES

In patients with chronic pancreatitis (CP), the aim was to explore the association between pancreatic morphological progression over four years and corresponding changes in disease characteristics, including quality of life (QOL), pain, and exocrine pancreatic function.

METHODS

Twenty-five patients with CP were followed by magnetic resonance imaging (MRI). Data were obtained at baseline and after 4-year follow-up, including clinical information, QOL, and pain as assessed by validated questionnaires. Morphological assessments were derived from the same MRI scanner and included pancreatic gland volume, apparent diffusion coefficient values, fat signal fraction, and main pancreatic duct diameter.

RESULTS

After four years, CP patients showed significant progression in morphological parameters of the pancreas, except for the ductal-related changes (p < .13). Hence, patients developed reduced pancreatic volume by 13.5% (p < .001), an increase of fibrosis by 10.8% (p < .001), and an increase of fat infiltration by 7.6% (p < .001). In contrast, the patient-reported outcomes of QOL and pain did not change significantly over four years (all p > .05). Moreover, the progression of morphological imaging findings was not related to changes in QOL, pain severity, and pain interference (all p > .05). There was, however, an association between the 4-year progression of pancreatic atrophy and the decrease in fecal elastase concentration (r = 0.61; p < .001).

CONCLUSIONS

Progression of gland morphology in CP did not correlate with changes in the quality of life or pain symptoms. Advanced pancreatic imaging techniques may be a highly sensitive tool for monitoring morphological disease progression, but do not directly reflect patients' disease burden.

Chronic pancreatitis: an overview of diagnosis and management

INTRODUCTION

Chronic pancreatitis entails a heavy burden on the healthcare system because of its often protracted evolution, requiring complex diagnostic and therapeutic procedures.

AREAS COVERED

This review focuses on novel imaging and endoscopic diagnostic and therapeutic interventions that have changed the management of patients with chronic pancreatitis. We have conducted an extensive search of original papers and guidelines, in order to provide a comprehensive and up to date review of available evidence in these areas of interest.

EXPERT OPINION

The traditional challenges in managing chronic pancreatitis patients stemmed from the limitations of diagnostic modalities, which could not correctly identify patients in an early stage of the disease, as well as from the scarcity of therapeutic options available. Advances in imaging of CT-scan, MRI, and EUS have opened the way for early diagnosis and staging. This has allowed more aggressive and tailored therapeutic modalities, particularly in endoscopic therapy and minimally invasive surgical interventions. Although high-quality data from large RCTs is still scarce, evidence-based algorithms for diagnosis and therapy are now changing the way we address this chronic disease. In the near future, we can expect a tailored approach based on patient and disease-related predictive factors, relying on a vast armamentarium of endoscopic and surgical solutions.

Pancreatic magnetic resonance imaging texture analysis in chronic pancreatitis: a feasibility and validation study

PURPOSE

This feasibility and validation study addresses the potential use of magnetic resonance imaging (MRI) texture analysis of the pancreas in patients with chronic pancreatitis (CP).

METHODS

Extraction of 851 MRI texture features from diffusion weighted imaging (DWI) of the pancreas was performed in 77 CP patients and 22 healthy controls. Features were reduced to classify patients into subgroups, and a Bayes classifier was trained using a tenfold cross-validation forward selection procedure. The classifier was optimized to obtain the best average m-fold accuracy, sensitivity, specificity, and positive predictive value. Classifiers were: presence of disease (CP vs. healthy controls), etiological risk factors (alcoholic vs. nonalcoholic etiology of CP and tobacco use vs. no tobacco use), and complications to CP (presumed pancreatogenic diabetes vs. no diabetes and pancreatic exocrine insufficiency vs. normal pancreatic function).

RESULTS

The best classification performance was obtained for the disease classifier selecting only five of the original features with 98% accuracy, 97% sensitivity, 100% specificity, and 100% positive predictive value. The risk factor classifiers obtained good performance using 9 (alcohol: 88% accuracy) and 10 features (tobacco: 86% accuracy). The two complication classifiers obtained similar accuracies with only 4 (diabetes: 83% accuracy) and 3 features (exocrine pancreatic function: 82% accuracy).

CONCLUSION

Pancreatic texture analysis demonstrated to be feasible in patients with CP and discriminate clinically relevant subgroups based on etiological risk factors and complications. In future studies, the method may provide useful information on disease progression (monitoring) and detection of biomarkers characterizing early-stage CP.

Cross-sectional imaging-based severity scoring of chronic pancreatitis: why it is necessary and how it can be done

Chronic pancreatitis (CP) remains a diagnostic challenge as clinical symptoms are non-specific, histopathological appearances are varied and pathogenesis remains incompletely understood. Multiple classifications and grading systems have been proposed for CP, but none leverage the full capabilities of cross-sectional imaging modalities and are not widely accepted or validated. CT and MRI/MRCP are useful in identifying a wide spectrum of histopathological changes in CP and can also assess exocrine reserve of pancreas. Advanced MRI techniques such as T1 mapping and extracellular volume fraction can potentially identify early CP. Cross-sectional imaging-based severity scoring can quantify CP disease burden and may have positive implications for clinicians and researchers. In this review, we discuss the need for cross-sectional imaging-based severity scoring for CP, role of CT, and MRI/MRCP in assessment of CP and how these modalities can be used to obtain severity scoring for CP. We summarize relevant information from recently published CT and MRI/MRCP reporting standards for CP, and from international guidelines for cross-sectional imaging and severity scoring for CP.

Progression of parenchymal and ductal findings in patients with chronic pancreatitis: A 4-year follow-up MRI study

PURPOSE

Knowledge of the underlying mechanisms behind progression of chronic pancreatitis (CP) is needed to identify targets for new mechanism-based treatments. There is an urgent need for imaging biomarkers that can detect early morphological and functional pancreatic damage in order to initiate intervention and reduce the progression of CP at an early stage. The aim of our study was to assess and explore the potential role of structural magnetic resonance imaging (MRI) biomarkers for characterisation of disease progression in a CP patient cohort over a 4-year period.

METHODS

This longitudinal MRI study included twenty-five patients with definitive CP. Assessments of morphological imaging parameters at baseline and after 4 years included pancreatic gland volume, apparent diffusion coefficient (ADC) values, fat signal fraction (FSF) and main pancreatic duct (MPD) diameter. Patients were classified according to the modified Cambridge classification.

RESULTS

CP patients developed significantly reduced pancreatic gland volume, which decreased from mean 50.3 ± 19.6 ml at baseline to 43.5 ± 20.8 ml at follow-up (P < 0.001), decreased ADC values, meaning a higher degree of fibrosis (P < 0.001), increased FSF, meaning more fat infiltration (P < 0.001) and higher Cambridge classification scores (P = 0.033). The MPD diameter in the pancreatic head, body and tail did not change significantly over time (all P > 0.05). Only few, but no clear and systematic, associations were found between the progressions of the individual MRI measures.

CONCLUSIONS

Morphological progression in patients with established CP seems to be primarily parenchymal-related. The different parenchymal changes were mostly unrelated and probably reflect diverse pathophysiological processes.

Placental diffusion-weighted MRI in normal pregnancies and those complicated by placental dysfunction due to vascular malperfusion

INTRODUCTION

Our aim was to assess placental function by diffusion-weighted magnetic resonance imaging (MRI) using intravoxel incoherent motion (IVIM) analysis in uncomplicated pregnancies and pregnancies complicated by placental dysfunction.

METHODS

31 normal pregnancies and 9 pregnancies complicated by placental dysfunction (birthweight ≤ -2SD and histological signs of placental vascular malperfusion) were retrieved from our placental MRI research database. MRI was performed at gestational weeks 20.1-40.6 in a 1.5 T system using 10 b-values (0-1000 s/mm²). Regions of interest were drawn covering the entire placenta in five transverse slices. Diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) were estimated by IVIM analysis.

RESULTS

In normal pregnancies, placental f decreased linearly with gestational age (r = -0.522, p = 0.002) being 26.2% at week 20 and 18.8% at week 40. D and D* were 1.57 ± 0.03 and 31.7 ± 3.1 mm²/s (mean ± SD), respectively, and they were not correlated with gestational age. In complicated pregnancies, f was significantly reduced (mean Z-score = -1.16; p = 0.02) when compared to the group of normal pregnancies, whereas D and D* did not differ significantly between groups. Subgroup analysis demonstrated that f was predominantly reduced in dysfunctional placentas characterized by fetal vascular malperfusion (mean Z-score = -2.11, p < 0.001) rather than maternal vascular malperfusion (mean Z-score = -0.40, p = 0.42). In addition, f was negatively correlated with uterine artery pulsatility index (r = -0.396, p = 0.01).

DISCUSSION

Among parameters obtained by the IVIM analysis, only f revealed significant differences between the normal and the dysfunctional placentas. Subgroup analysis suggests that placental f may be able to discriminate non-invasively between different histological types of vascular malperfusion.

CT- and MRI-Based Assessment of Body Composition and Pancreatic Fibrosis Reveals High Incidence of Clinically Significant Metabolic Changes That Affect the Quality of Life and Treatment Outcomes of Patients with Chronic Pancreatitis and Pancreatic Cancer

Background and Objectives: Both chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) may lead to cachexia, sarcopenia, and osteoporosis due to different mechanisms. Neither patient gender, age, nor body weight are good predictors of these metabolic changes having a significant negative impact on the quality of life (QOL) and treatment outcomes. The aim of this study was to evaluate radiological changes in body composition and to compare them with manifestations of exocrine and endocrine pancreatic insufficiency, body mass, and QOL among patients with CP and PDAC. Materials and Methods: Prospectively collected data of 100 patients with diagnosed CP or PDAC were used for analysis. All patients underwent dual-energy X-ray absorptiometry (DXA), computed tomography (CT), and magnetic resonance imaging (MRI). The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30) was used to assess QOL. Diabetes and changes in fecal elastase-1 were also assessed. Results: There was no significant difference in skeletal muscle mass (SMM) among patients with CP and PDAC (p = 0.85). Significantly more underweight patients had low SMM (p = 0.002). Patients with CP had more pronounced pancreatic fibrosis (PF) (p < 0.001). Data showed a significant relationship between a high degree of PF and occurrence of diabetes (p = 0.006) and low fecal elastase-1 levels (p = 0.013). A statistically significant lower QOL was determined in patients with PF ≥ 50% and in the CP group. Conclusions: Sarcopenia and osteoporosis/osteopenia are highly prevalent among patients with chronic pancreatitis and pancreatic cancer, and CT- and MRI-based assessment of body composition and pancreatic fibrosis could be a potentially useful tool for routine detection of these significant metabolic changes.