Magnetic resonance imaging: a reliable method for measuring pancreatic volume in Type 1 diabetes

Cross-sectional imaging of the pancreas in diabetes

Diabetes mellitus presents a global health challenge characterized by dysregulated glucose metabolism and insulin resistance. Pancreas dysfunction contributes to the development and progression of diabetes. Cross-sectional imaging modalities have provided new insight into the structural and functional alterations of the pancreas in individuals with diabetes. This review summarizes MRI and CT studies that characterize pancreas alterations in both type 1 and type 2 diabetes and discusses future applications of these techniques.

Conflicting Views About Interactions Between Pancreatic α-Cells and β-Cells

In type 1 diabetes, the reduced glucagon response to insulin-induced hypoglycemia has been used to argue that β-cell secretion of insulin is required for the full glucagon counterregulatory response. For years, the concept has been that insulin from the β-cell core flows downstream to suppress glucagon secretion from the α-cells in the islet mantle. This core-mantle relationship has been supported by perfused pancreas studies that show marked increases in glucagon secretion when insulin was neutralized with antisera. Additional support comes from a growing number of studies focused on vascular anatomy and blood flow. However, in recent years this core-mantle view has generated less interest than the argument that optimal insulin secretion is due to paracrine release of glucagon from α-cells stimulating adjacent β-cells. This mechanism has been evaluated by knockout of β-cell receptors and impairment of α-cell function by inhibition of Gi designer receptors exclusively activated by designer drugs. Other studies that support this mechanism have been obtained by pharmacological blocking of glucagon-like peptide 1 receptor in humans. While glucagon has potent effects on β-cells, there are concerns with the suggested paracrine mechanism, since some of the supporting data are from isolated islets. The study of islets in static incubation or perifusion systems can be informative, but the normal paracrine relationships are disrupted by the isolation process. While this complicates interpretation of data, arguments supporting paracrine interactions between α-cells and β-cells have growing appeal. We discuss these conflicting views of the relationship between pancreatic α-cells and β-cells and seek to understand how communication depends on blood flow and/or paracrine mechanisms.

Longitudinal MRI Shows Progressive Decline in Pancreas Size and Altered Pancreas Shape in Type 1 Diabetes

CONTEXT

Individuals with type 1 diabetes (T1D) have a smaller pancreas, but longitudinal changes in pancreas size and shape are unclear.

OBJECTIVE

We monitored changes in pancreas size and shape after diagnosis with T1D.

DESIGN

We conducted a prospective cohort study at an academic medical center between 2014 and 2022.

PATIENTS AND HEALTHY CONTROLS

Individuals with T1D (n = 91) or controls (n = 90) underwent magnetic resonance imaging (MRI) of the pancreas, including longitudinal MRI in 53 individuals with new-onset T1D.

INTERVENTION

Interventions included MRI and continuous glucose monitoring (CGM).

MAIN OUTCOME MEASURES

Pancreas size and shape were measured from MRI. For participants who used CGM, measures of glycemic variability were calculated.

RESULTS

On longitudinal imaging, pancreas volume and pancreas volume index normalized for body weight declined during the first year after diagnosis. Pancreas volume index continued to decline through the fifth year after diagnosis. A cross-sectional study of individuals with diabetes duration up to 60 years demonstrated that pancreas size in adults negatively correlated with age and disease duration, whereas pancreas volume and pancreas volume index remained stable in controls. Pancreas volume index correlated inversely with low blood glucose index, a measure of risk for hypoglycemia. Pancreas shape was altered in individuals with T1D and further diverged from controls over the first 5 years after diagnosis. Pancreas size and shape are altered in nondiabetic individuals at genetic risk for T1D. Combined pancreas size and shape analysis better distinguished the pancreas of individuals with T1D from controls than size alone.

CONCLUSIONS

Pancreas size declines most rapidly near the clinical diagnosis of T1D and continues to decline throughout adulthood. Declines in pancreas size are accompanied by changes in pancreas shape.

Association between Hyperglycemia and Canine Serum Pancreatic Lipase Immunoreactivity Concentration in Diabetic Dogs

It has been reported that hypertriglyceridemia can partially mediate between diabetes mellitus (DM) and pancreatitis in dogs, implying that another mediator, such as chronic hyperglycemia, might exist. Therefore, this study aimed to evaluate the relationship between hyperglycemia and serum canine pancreatic lipase immunoreactivity (cPLI) concentration in diabetic dogs. This retrospective cohort study included 26 client-owned diabetic dogs, divided according to their serum fructosamine levels (<500 μmol/L = well-controlled DM group; ≥500 μmol/L = untreated or poorly controlled DM group). Five of the 26 DM dogs (19.2%) had serum cPLI concentrations consistent with pancreatitis, among which two showed ultrasonographic evidence of pancreatitis without clinical signs. The serum cPLI concentrations (median [interquartile range]) were significantly higher in the untreated or poorly controlled group (520 μg/L [179.76-1000 μg/L]) than in the well-controlled group (77 μg/L [32.22-244.6 μg/L], P = 0.0147). The serum fructosamine concentration was positively correlated with the serum cPLI concentration (r = 0.4816; P = 0.0127). Multivariate analysis revealed serum triglyceride and fructosamine concentrations were associated with the serum cPLI concentration. In conclusion, this study suggests that chronic hyperglycemia may induce pancreatic inflammation in diabetic dogs; however, the clinical significance of increased cPLI concentration is unknown.

A novel bioartificial pancreas fabricated via islets microencapsulation in anti-adhesive core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo

Islets transplantation is a promising treatment for type 1 diabetes mellitus. However, severe host immune rejection and poor oxygen/nutrients supply due to the lack of surrounding capillary network often lead to transplantation failure. Herein, a novel bioartificial pancreas is constructed via islets microencapsulation in core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo. Specifically, a hydrogel scaffold containing methacrylated gelatin (GelMA), methacrylated heparin (HepMA) and vascular endothelial growth factor (VEGF) is fabricated, which can delivery VEGF in a sustained style and thus induce subcutaneous angiogenesis. In addition, islets-laden core-shell microgels using methacrylated hyaluronic acid (HAMA) as microgel core and poly(ethylene glycol) diacrylate (PEGDA)/carboxybetaine methacrylate (CBMA) as shell layer are prepared, which provide a favorable microenvironment for islets and simultaneously the inhibition of host immune rejection via anti-adhesion of proteins and immunocytes. As a result of the synergistic effect between anti-adhesive core-shell microgels and prevascularized hydrogel scaffold, the bioartificial pancreas can reverse the blood glucose levels of diabetic mice from hyperglycemia to normoglycemia for at least 90 days. We believe this bioartificial pancreas and relevant fabrication method provide a new strategy to treat type 1 diabetes, and also has broad potential applications in other cell therapies.

The importance of biomarker development for monitoring type 1 diabetes progression rate and therapeutic responsiveness

Type 1 diabetes (T1D) is an autoimmune condition of children and adults in which immune cells target insulin-producing pancreatic β-cells for destruction. This results in a chronic inability to regulate blood glucose levels. The natural history of T1D is well-characterized in childhood. Evidence of two or more autoantibodies to the islet antigens insulin, GAD, IA-2 or ZnT8 in early childhood is associated with high risk of developing T1D in the future. Prediction of risk is less clear in adults and, overall, the factors controlling the progression rate from multiple islet autoantibody positivity to onset of symptoms are not fully understood. An anti-CD3 antibody, teplizumab, was recently shown to delay clinical progression to T1D in high-risk individuals including adults and older children. This represents an important proof of concept for those at risk of future T1D. Given their role in risk assessment, islet autoantibodies might appear to be the most obvious biomarkers to monitor efficacy. However, monitoring islet autoantibodies in clinical trials has shown only limited effects, although antibodies to the most recently identified autoantigen, tetraspanin-7, have not yet been studied in this context. Measurements of beta cell function remain fundamental to assessing efficacy and different models have been proposed, but improved biomarkers are required for both progression studies before onset of diabetes and in therapeutic monitoring. In this mini-review, we consider some established and emerging predictive and prognostic biomarkers, including markers of pancreatic function that could be integrated with metabolic markers to generate improved strategies to measure outcomes of therapeutic intervention.

Imaging Methods Applicable in the Diagnostics of Alzheimer's Disease, Considering the Involvement of Insulin Resistance

Alzheimer's disease (AD) is an incurable neurodegenerative disease and the most frequently diagnosed type of dementia, characterized by (1) perturbed cerebral perfusion, vasculature, and cortical metabolism; (2) induced proinflammatory processes; and (3) the aggregation of amyloid beta and hyperphosphorylated Tau proteins. Subclinical AD changes are commonly detectable by using radiological and nuclear neuroimaging methods such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and single-photon emission computed tomography (SPECT). Furthermore, other valuable modalities exist (in particular, structural volumetric, diffusion, perfusion, functional, and metabolic magnetic resonance methods) that can advance the diagnostic algorithm of AD and our understanding of its pathogenesis. Recently, new insights into AD pathoetiology revealed that deranged insulin homeostasis in the brain may play a role in the onset and progression of the disease. AD-related brain insulin resistance is closely linked to systemic insulin homeostasis disorders caused by pancreas and/or liver dysfunction. Indeed, in recent studies, linkages between the development and onset of AD and the liver and/or pancreas have been established. Aside from standard radiological and nuclear neuroimaging methods and clinically fewer common methods of magnetic resonance, this article also discusses the use of new suggestive non-neuronal imaging modalities to assess AD-associated structural changes in the liver and pancreas. Studying these changes might be of great clinical importance because of their possible involvement in AD pathogenesis during the prodromal phase of the disease.

Imaging evaluation of the pancreas in diabetic patients

Diabetes mellitus (DM) is becoming a global epidemic and its diagnosis and monitoring are based on laboratory testing which sometimes have limitations. The pancreas plays a key role in metabolism and is involved in the pathogenesis of DM. It has long been known through cadaver biopsies that pancreas volume is decreased in patients with DM. With the development of different imaging modalities over the last two decades, many studies have attempted to determine whether there other changes occurred in the pancreas of diabetic patients. This review summarizes current knowledge about the use of different imaging approaches (such as CT, MR, and US) and radiomics for exploring pancreatic changes in diabetic patients. Imaging studies are expected to produce reliable information regarding DM, and radiomics could provide increasingly valuable information to identify some undetectable features and help diagnose and predict the occurrence of diabetes through pancreas imaging.

Histological and transcriptional characterization of the pancreatic acinar tissue in type 1 diabetes

INTRODUCTION

Despite a reduced function and volume of the exocrine pancreas in type 1 diabetes, the acinar cells remain understudied in type 1 diabetes research. The hypothesis of this study is that the acinar tissue is altered in subjects with type 1 diabetes compared with subjects without diabetes.

RESEARCH DESIGN AND METHODS

The cell density, expression of digestive enzymes, and transcriptome of acinar tissue at varying distances from islets were analyzed using histology, immunostaining, and AmpliSeq RNA sequencing of laser capture microdissected tissue. Pancreases examined were from organ donors with or without type 1 diabetes.

RESULTS

We demonstrate preserved acinar nuclei density and find no support of acinar atrophy in type 1 diabetes. Staining for digestive enzymes (amylase, lipase, and trypsin) demonstrated an evenly distributed expression in the exocrine parenchyma; although occasional amylase-negative regions appeared in tissue that had been formalin-fixed and paraffin-embedded, this phenomenon was not evident in frozen tissue. Gene set enrichment analysis of whole transcriptome data identified transcriptional alterations in type 1 diabetes that were present in the acinar tissue independent of the distance from islets. Among these, the two most enriched gene sets were Myc Targets V2 and Estrogen Response Early.

CONCLUSION

Taken together, these new data emphasize the involvement of the entire pancreas in type 1 diabetes pathology. The alteration of the gene sets Myc Targets V2 and Estrogen Response Early is a possible link to the increased incidence of pancreatic cancer in type 1 diabetes.

No effects of a 6-week intervention with a glucagon-like peptide-1 receptor agonist on pancreatic volume and oedema in obese men without diabetes

AIM

To investigate the effect of a glucagon-like peptide-1 receptor agonist (GLP-1RA), liraglutide, on pancreatic volume, oedema, cellularity and DNA synthesis in humans.

MATERIALS AND METHODS

We performed an open-label study in 14 obese men (age 38 ± 11 years, body mass index 32 ± 4 kg/m² ) without diabetes. Subjects were examined at baseline, during titration (week 4) of liraglutide towards 3.0 mg/day, and 2 weeks after steady-state treatment (week 6) of a final dose of liraglutide. The primary endpoint was pancreatic volume determined by magnetic resonance imaging. Secondary endpoints included pancreatic oedema and cellularity, positron emission tomography-based [¹⁸ F]fluorothymidine (FLT) uptake (DNA synthesis) and plasma pancreatic enzymes.

RESULTS

Plasma amylase (+7 U/L [95% confidence intervals 3-11], P < .01) and lipase (+19 U/L [7-30], P < .01) increased during liraglutide treatment. Pancreatic volume did not change from baseline to steady state of treatment (+0.2 cm³ [-8-8], P = .96) and no change in pancreatic cellular infiltration was found (P = .22). During titration of liraglutide, FLT uptake in pancreatic tissue increased numerically (+0.08 [0.00-0.17], P = .0507).

CONCLUSIONS

Six weeks of treatment with liraglutide did not affect pancreatic volume, oedema or cellularity in obese men without diabetes.

Pancreatic atrophy after gastrectomy for gastric cancer

PURPOSE

To investigate the phenomenon of pancreatic atrophy after gastrectomy for gastric cancer, using computed tomography (CT) volumetry.

METHODS

The subjects of this retrospective study were 77 patients who underwent distal gastrectomy (DG) or total gastrectomy (TG) for pStage I gastric cancer in 2014. The relative pancreatic volume ratio was assessed preoperatively, and then 1 and 5 years postoperatively and the results were compared between surgical procedures RESULTS: A total of 14 patients underwent TG with Roux-en-Y (RY) reconstruction, 24 underwent DG with Billroth-I (BI) reconstruction, and 39 underwent DG with RY reconstruction. We observed that the pancreatic volume continued to decrease over the 5 years after DG or TG. Furthermore, the incidence of pancreatic atrophy 5 years postoperatively was significantly greater after TG than after DG. In patients who underwent DG, a greater incidence of pancreatic atrophy was observed after RY reconstruction than after BI reconstruction, 5 years postoperatively.

CONCLUSION

The pancreatic volume continued to decrease after DG and TG for gastric cancer 5 years after treatment. TG was associated with a significantly greater incidence of pancreatic atrophy than DG 5 years postoperatively, as was RY reconstruction vs. BI reconstruction after DG.

Healthy pancreatic parenchymal volume and its relationship to exocrine function

BACKGROUND

Pancreatic atrophy as a finding of chronic pancreatitis has largely been a subjective finding. Cross-sectional imaging should provide a means to quantify pancreatic atrophy.

OBJECTIVE

The purposes of this study were to: (1) quantify pancreatic volume by magnetic resonance imaging (MRI) in a cohort of children without pancreatic disease, (2) define predictors of pancreatic volume and (3) assess the relationship between pancreatic volume and pancreatic fluid secretion.

MATERIALS AND METHODS

This study involved further analysis of data collected as part of an institutional review board-approved prospective study of secreted fluid volume in response to secretin in 50 healthy children ages 6-16 years. The pancreas was manually segmented on axial MR images to calculate pancreatic volume. Pearson correlation or the Student's t-test were used to define associations between pancreatic volume and patient characteristics and previously calculated secreted fluid volume. Quantile regression was used to define the 5th percentile for pancreatic volume based on body surface area (BSA) [1].

RESULTS

Mean pancreatic volume was 46.0±18.8 mL with no significant difference based on sex (boys: 42.4±19 mL, girls: 49.1±18.3 mL, P=0.21). Pancreatic volume was moderately correlated with age (r=0.51, P=0.002) and strongly correlated with BSA (r=0.75, P<0.0001), with the 5th percentile for pancreatic volume defined by: (24.66×BSA) - 4.97. Pancreatic volume was moderately correlated with volume of fluid secreted after secretin administration (r=0.51, P=0.0002).

CONCLUSION

We report increasing pancreatic volumes by MRI during childhood in a cohort of children without pancreatic disease. We have also shown that pancreatic volume is associated with secreted fluid volume as measured by MRI.

From immunohistological to anatomical alterations of human pancreas in type 1 diabetes: New concepts on the stage

The histological analysis of human pancreatic samples in type 1 diabetes (T1D) has been proven essential to move forward in the evaluation of in situ events characterizing T1D. Increasing availability of pancreatic tissues collected from diabetic multiorgan donors by centralized biorepositories, which have shared tissues among researchers in the field, has allowed a deeper understanding of T1D pathophysiology, using novel immunohistological and high-throughput methods. In this review, we provide a comprehensive update of the main recent advancements in the characterization of cellular and molecular events involving endocrine and exocrine pancreas as well as the immune system in the onset and progression of T1D. Additionally, we underline novel elements, which provide evidence that T1D pathological changes affect not only islet β-cells but also the entire pancreas.

Repeatability and Reproducibility of Pancreas Volume Measurements Using MRI

Reduced pancreas volume, as measured by non-contrast magnetic resonance imaging (MRI), is observed in individuals with newly-diagnosed type 1 diabetes (T1D) and declines over the first year after diagnosis. In this study, we determined the repeatability and inter-reader reproducibility of pancreas volume measurements by MRI. Test-retest scans in individuals with or without T1D (n = 16) had an intraclass correlation coefficient (ICC) of 0.985 (95% CI 0.961 to 0.995) for pancreas volume. Independent pancreas outlines by two board-certified radiologists (n = 30) yielded an ICC of 0.945 (95% CI 0.889 to 0.973). The mean Dice coefficient, a measurement of the degree of overlap between pancreas regions of interest between the two readers, was 0.77. Prandial state did not influence pancreatic measurements, as stomach volume did not correlate with pancreas volume. These data demonstrate that MRI measurements of pancreas volume between two readers are repeatable and reproducible with ICCs that correspond to excellent clinical significance (ICC > 0.9), are not related to changes in stomach volume, and could be a useful tool for clinical investigation of diabetes and other pancreas pathologies.

New Frontiers in the Treatment of Type 1 Diabetes

Type 1 diabetes is an autoimmune disease caused by the immune-mediated destruction of pancreatic β cells that results in lifelong absolute insulin deficiency. For nearly a century, insulin replacement has been the only therapy for most people living with this disease. Recent advances in technology and our understanding of β cell development, glucose metabolism, and the underlying immune pathogenesis of the disease have led to innovative therapeutic and preventative approaches. A paradigm shift in immunotherapy development toward the targeting of islet-specific immune pathways involved in tolerance has driven the development of therapies that may allow for the prevention or reversal of this disease while avoiding toxicities associated with historical approaches that were broadly immunosuppressive. In this review, we discuss successes, failures, and emerging pharmacological therapies for type 1 diabetes that are changing how we approach this disease, from improving glycemic control to developing the "holy grail" of disease prevention.

Quantitative Magnetic Resonance Imaging of the Pancreas of Individuals With Diabetes

Magnetic resonance imaging (MRI) has the potential to improve our understanding of diabetes and improve both diagnosis and monitoring of the disease. Although the spatial resolution of MRI is insufficient to directly image the endocrine pancreas in people, the increasing awareness that the exocrine pancreas is also involved in diabetes pathogenesis has spurred new MRI applications. These techniques build upon studies of exocrine pancreatic diseases, for which MRI has already developed into a routine clinical tool for diagnosis and monitoring of pancreatic cancer and pancreatitis. By adjusting the imaging contrast and carefully controlling image acquisition and processing, MRI can quantify a variety of tissue pathologies. This review introduces a number of quantitative MRI techniques that have been applied to study the diabetic pancreas, summarizes progress in validating and standardizing each technique, and discusses the need for image analyses that account for spatial heterogeneity in the pancreas.

Molecular imaging of β-cells: diabetes and beyond

Since diabetes is becoming a global epidemic, there is a great need to develop early β-cell specific diagnostic techniques for this disorder. There are two types of diabetes (i.e., type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM)). In T1DM, the destruction of pancreatic β-cells leads to reduced insulin production or even absolute insulin deficiency, which consequently results in hyperglycemia. Actually, a central issue in the pathophysiology of all types of diabetes is the relative reduction of β-cell mass (BCM) and/or impairment of the function of individual β-cells. In the past two decades, scientists have been trying to develop imaging techniques for noninvasive measurement of the viability and mass of pancreatic β-cells. Despite intense scientific efforts, only two tracers for positron emission tomography (PET) and one contrast agent for magnetic resonance (MR) imaging are currently under clinical evaluation. β-cell specific imaging probes may also allow us to precisely and specifically visualize transplanted β-cells and to improve transplantation outcomes, as transplantation of pancreatic islets has shown promise in treating T1DM. In addition, some of these probes can be applied to the preoperative detection of hidden insulinomas as well. In the present review, we primarily summarize potential tracers under development for imaging β-cells with a focus on tracers for PET, SPECT, MRI, and optical imaging. We will discuss the advantages and limitations of the various imaging probes and extend an outlook on future developments in the field.

Association between Pancreatic Atrophy and Loss of Insulin Secretory Capacity in Patients with Type 2 Diabetes Mellitus

AIMS

To examine pancreatic volume (PV) changes among patients with different duration of type 2 diabetes and whether pancreatic atrophy was associated with loss of insulin secretory capacity.

METHODS

This cross-sectional study (203 patients with type 2 diabetes, 93 controls without diabetes) was conducted from January 2016 to December 2017. Patients with type 2 diabetes were divided into 3 groups: recently diagnosed (duration ≤ 2 years), midterm (duration 3-9 years), and long term (duration ≥ 10 years). All the patients were scanned with upper abdominal computerized tomography; PV was then calculated by an experienced technician. Absolute insulin deficiency was defined as fasting C - peptide < 0.9 ng/mL.

RESULTS

Compared with PV (cm³) in the controls, the mean PV was similar in patients with recently diagnosed type 2 diabetes (68.8 versus 71.0, P = 0.56) but significantly reduced in patients with midterm (68.8 versus 60.8, P < 0.05) and long-term (68.8 versus 53.1, P < 0.001) type 2 diabetes. A similar trend was observed for the PV index (PV adjusted for body surface area and body mass index). Furthermore, rates of pancreatic atrophy and absolute insulin deficiency increased with duration of diabetes. Multiple logistic regression analysis indicated that pancreatic atrophy was associated with higher likelihood of absolute insulin deficiency (odds ratio = 4.47, 95%confidence interval = 1.45-13.8).

CONCLUSIONS

PV was reduced in those with midterm and long-term type 2 diabetes compared to individuals without type 2 diabetes. Overall, pancreatic atrophy was associated with the loss of insulin secretory capacity in patients with type 2 diabetes.

Pancreas volume in health and disease: a systematic review and meta-analysis

The pancreas plays a central role in metabolism and is involved in the pathogenesis of several diseases. Pancreas volume is a holistic quantitative measure of pancreas size but the clinical relevance of pancreas volumetry is poorly understood. Areas covered: The aim was to systematically review studies in adults that used computed tomography or magnetic resonance imaging to measure pancreas volume in health and disease, to determine normal pancreas volume range, and to quantify changes in pancreas volume that are associated with disease. Expert commentary: The normal pancreas volume range in adults is 71-83 cm³, with no statistically significant difference between men and women. Type 2 diabetes and type 1 diabetes are associated with a progressively reduced pancreas volume. Overweight and obesity are associated with a progressively increased pancreas volume. There is a paucity of studies on pancreas volume in the setting of diseases of the exocrine pancreas, which should become a research priority in the future.

Exocrine pancreatic insufficiency in type 1 and type 2 diabetes mellitus: do we need to treat it? A systematic review

The exocrine and endocrine pancreata are very closely linked both anatomically and physiologically. Abdominal symptoms such as nausea, bloating, diarrhea, steatorrhea, and weight loss can often occur in diabetic patients. Impairments of the exocrine pancreatic function seem to be a frequent complication of diabetes mellitus; however, they are largely overlooked. The aim of this paper is to provide an overview of the current concepts of exocrine pancreatic insufficiency (PEI) in diabetes mellitus. The prevalence and symptoms of PEI in diabetes mellitus, the pathomechanism, and difficulties of diagnosis and therapy of PEI are summarized in this systematic review.

Aetiology of type 1 diabetes: Physiological growth in children affects disease progression

The prevailing view is that type 1 diabetes (T1D) develops as a consequence of a severe decline in β-cell mass resulting from T-cell-mediated autoimmunity; however, progression from islet autoantibody seroconversion to overt diabetes and finally to total loss of C-peptide production occurs in most affected individuals only slowly over many years or even decades. This slow disease progression should be viewed in relation to the total β-cell mass of only 0.2 to 1.5 g in adults without diabetes. Focal lesions of acute pancreatitis with accumulation of leukocytes, often located around the ducts, are frequently observed in people with recent-onset T1D, and most patients display extensive periductal fibrosis, the end stage of inflammation. An injurious inflammatory adverse event, occurring within the periductal area, may have negative implications for islet neogenesis, dependent on stem cells residing within or adjacent to the ductal epithelium. This could in part prevent the 30-fold increase in β-cell mass that would normally occur during the first 20 years of life. This increase occurs in order to maintain glucose metabolism during the physiological increases in insulin production that are required to balance the 20-fold increase in body weight during childhood and increased insulin resistance during puberty. Failure to expand β-cell mass during childhood would lead to clinically overt T1D and could help to explain the apparently more aggressive form of T1D occurring in growing children when compared with that observed in affected adults.

Pancreatic size and fat content in diabetes: A systematic review and meta-analysis of imaging studies

Objectives

Imaging studies are expected to produce reliable information regarding the size and fat content of the pancreas. However, the available studies have produced inconclusive results. The aim of this study was to perform a systematic review and meta-analysis of imaging studies assessing pancreas size and fat content in patients with type 1 diabetes (T1DM) and type 2 diabetes (T2DM).

Methods

Medline and Embase databases were performed. Studies evaluating pancreatic size (diameter, area or volume) and/or fat content by ultrasound, computed tomography, or magnetic resonance imaging in patients with T1DM and/or T2DM as compared to healthy controls were selected. Seventeen studies including 3,403 subjects (284 T1DM patients, 1,139 T2DM patients, and 1,980 control subjects) were selected for meta-analyses. Pancreas diameter, area, volume, density, and fat percentage were evaluated.

Results

Pancreatic volume was reduced in T1DM and T2DM vs. controls (T1DM vs. controls: -38.72 cm3, 95%CI: -52.25 to -25.19, I2 = 70.2%, p for heterogeneity = 0.018; and T2DM vs. controls: -12.18 cm3, 95%CI: -19.1 to -5.25, I2 = 79.3%, p for heterogeneity = 0.001). Fat content was higher in T2DM vs. controls (+2.73%, 95%CI 0.55 to 4.91, I² = 82.0%, p for heterogeneity<0.001).

Conclusions

Individuals with T1DM and T2DM have reduced pancreas size in comparison with control subjects. Patients with T2DM have increased pancreatic fat content.

Chronic Pancreatitis-Like Changes Detected by Endoscopic Ultrasound in Type 1 Diabetics Are Not Associated With Gastrointestinal Symptoms or Nutritional Deficiencies

OBJECTIVES

Previous studies have shown changes in the pancreas of type 1 diabetic (T1-DM) patients, similar to those present in patients with chronic pancreatitis. Our aim was to analyze the prevalence of endoscopic ultrasound (EUS) criteria for chronic pancreatitis in T1-DM, to determine the association with factors related to the diabetes and to define its clinical significance.

METHODS

Eighty-six T1-DM patients were prospectively included. All of them underwent EUS. Standard criteria were used. Patients were divided into 3 groups according to the number of EUS criteria they met: group A, 0 to 2 criteria; group B, 3 to 4; and group C, more than 4. Association between EUS findings and demographic or clinical factors was studied as well as the relationship between EUS abnormalities and the presence of gastrointestinal symptoms or nutritional deficiencies.

RESULTS

Fifty-three patients (61.6%) showed at least 1 morphologic abnormality. Fifty-eight patients were included in group A, 21 in group B, and 7 in Group C. No significant differences were found when comparing the 3 groups.

CONCLUSIONS

Chronic pancreatitis-like changes are frequent in the pancreas of T1-DM patients. These changes are not associated with demographic or clinical data. Therefore, the clinical relevance seems to be scarce.

Pancreatic volume is reduced in patients with latent autoimmune diabetes in adults

AIMS

This study aimed to compare pancreatic volume and its clinical significance among patients with type 2 diabetes mellitus (DM), adult-onset type 1 DM and latent autoimmune diabetes in adults (LADA).

METHODS

This is a cross-sectional study. One hundred twenty-six outpatients (68 with LADA and 58 with type 1 DM) and 158 inpatients (71 with type 2 DM and 87 non-diabetic controls) were recruited during May-July 2013 in Shanghai Jiao Tong University Affiliated Sixth People's Hospital. All the patients underwent abdominal computerized tomography; pancreatic volume was then calculated.

RESULTS

The mean pancreatic volume was highest in the controls, followed by those in patients with type 2 DM, LADA and type 1 DM. The pancreatic volume in LADA was comparable with that in type 2 DM but significantly greater than that in type 1 DM (p < 0.05). The pancreatic volume in patients with LADA was significantly correlated with sex, waist circumference, body surface area, body mass index, diastolic blood pressure and high-density lipoprotein cholesterol (all p < 0.05). The correlation between pancreatic volume and fasting C-peptide was high in patients with LADA (r = 0.643, p < 0.001) and moderate in patients with type 2 DM (r = 0.467, p < 0.001). The area under the receiver operating characteristic curve for pancreatic volume predictive of absolute insulin deficiency (FCP < 0.9 ng/mL) was 0.85 (0.76-0.94) in LADA.

CONCLUSIONS

Pancreatic atrophy in LADA was less marked than in type 1 DM. Pancreatic atrophy may suggest reduced level of fasting C-peptide in patients with LADA. Copyright © 2016 John Wiley & Sons, Ltd.

Diabetes Mellitus Is Associated With an Exocrine Pancreatopathy: Conclusions From a Review of Literature

OBJECTIVE

Abnormalities in exocrine pancreatic function have been reported in diabetes mellitus (DM). We reviewed published literature to determine the nature of structural and functional alterations in the exocrine pancreas in DM.

METHODS

We identified and abstracted data from original studies (n = 50) describing morphological, structural, and functional changes in the exocrine pancreas in types 1 and 2 DM.

RESULTS

Pancreatic weight and volume are markedly lower in type 1 DM (P < 0.005) with insignificant decrease in type 2 DM compared with age-, sex-, and body mass index-matched controls. Pancreatic histopathological changes seen in most subjects with DM at autopsy (n = 7 studies, 1272 autopsies) include mild-to-marked interacinar fibrosis, scant inflammatory infiltrate, no pancreatic ductal changes, and hyalinization of arteries. In subjects with DM, pooled prevalence of decreased fecal elastase 1 (<200 μg/g) is higher, coefficient of fat absorption is near normal (mean, 91%-94%), and pancreatic exocrine dysfunction is nonprogressive over time. Diabetes mellitus is asymptomatic in regard to the exocrine pancreas.

CONCLUSIONS

In types 1 and 2 DM, moderate-to-severe subclinical pancreatic fibrosis and modest exocrine dysfunction occurs in the absence of clinical or histopathological evidence of chronic pancreatitis. We call this novel entity "diabetic exocrine pancreatopathy."

Morphology of the pancreas in type 2 diabetes: effect of weight loss with or without normalisation of insulin secretory capacity

AIMS/HYPOTHESIS

This study was designed to establish whether the low volume and irregular border of the pancreas in type 2 diabetes would be normalised after reversal of diabetes.

METHODS

A total of 29 individuals with type 2 diabetes undertook a very low energy (very low calorie) diet for 8 weeks followed by weight maintenance for 6 months. Methods were established to quantify the pancreas volume and degree of irregularity of the pancreas border. Three-dimensional volume-rendering and fractal dimension (FD) analysis of the MRI-acquired images were employed, as was three-point Dixon imaging to quantify the fat content.

RESULTS

There was no change in pancreas volume 6 months after reversal of diabetes compared with baseline (52.0 ± 4.9 cm(3) and 51.4 ± 4.5 cm(3), respectively; p = 0.69), nor was any volumetric change observed in the non-responders. There was an inverse relationship between the volume and fat content of the pancreas in the total study population (r =-0.50, p = 0.006). Reversal of diabetes was associated with an increase in irregularity of the pancreas borders between baseline and 8 weeks (FD 1.143 ± 0.013 and 1.169 ± 0.006, respectively; p = 0.05), followed by a decrease at 6 months (1.130 ± 0.012, p = 0.006). On the other hand, no changes in FD were seen in the non-reversed group.

CONCLUSIONS/INTERPRETATION

Restoration of normal insulin secretion did not increase the subnormal pancreas volume over 6 months in the study population. A significant change in irregularity of the pancreas borders occurred after acute weight loss only after reversal of diabetes. Pancreas morphology in type 2 diabetes may be prognostically important, and its relationship to change in beta cell function requires further study.

Use of the Electronic Medical Record to Assess Pancreas Size in Type 1 Diabetes

Aims

This study harnessed the electronic medical record to assess pancreas volume in patients with type 1 diabetes (T1D) and matched controls to determine whether pancreas volume is altered in T1D and identify covariates that influence pancreas volume.

Methods

This study included 25 patients with T1D and 25 age-, sex-, and weight-matched controls from the Vanderbilt University Medical Center enterprise data warehouse. Measurements of pancreas volume were made from medical imaging studies using magnetic resonance imaging (MRI) or computed tomography (CT).

Results

Patients with T1D had a pancreas volume 47% smaller than matched controls (41.16 ml vs. 77.77 ml, P < 0.0001) as well as pancreas volume normalized by subject body weight, body mass index, or body surface area (all P < 0.0001). Pancreatic volume was smaller with a longer duration of T1D across the patient population (N = 25, P = 0.04). Additionally, four individual patients receiving multiple imaging scans displayed progressive declines in pancreas volume over time (~ 6% of volume/year), whereas five controls scanned a year apart did not exhibit a decline in pancreas size (P = 0.03). The pancreas was uniformly smaller on the right and left side of the abdomen.

Conclusions

Pancreas volume declines with disease duration in patients with T1D, suggesting a protracted pathological process that may include the exocrine pancreas.

A run on the biobank: what have we learned about type 1 diabetes from the nPOD tissue repository?

PURPOSE OF REVIEW

Since the inaugural year of its biobank in 2007, the Network for Pancreatic Organ Donors with Diabetes program has provided 70 370 human samples to 127 investigators worldwide for projects focused on the pathogenesis of type 1 diabetes (T1D). The purpose of this review was to highlight major advances in our understanding of T1D using works that contain original data from experiments utilizing biospecimens provided by the Network for Pancreatic Organ Donors with Diabetes program. A total of 15 studies, published between 1 June 2013 and 31 December 2014, were selected using various search and filter strategies.

RECENT FINDINGS

The type and frequency of B and/or T-cell immune markers in both the endocrine and exocrine compartments vary in T1D. Enterovirus signals have been identified as having new proteins in the extracellular matrix around infiltrated islets. Novel genes within human islet cell types have been shown to play a role in immunity, infiltration, inflammation, disease progression, cell mass and function. Various cytokines and a complement degradation product have also been detected in the blood or surrounding pancreatic ducts/vasculature.

SUMMARY

These findings, from T1D donors across the disease spectrum, emphasize the notion that pathogenic heterogeneity is a hallmark of the disorder.

Noninvasive mapping of pancreatic inflammation in recent-onset type-1 diabetes patients

The inability to visualize the initiation and progression of type-1 diabetes (T1D) noninvasively in humans is a major research and clinical stumbling block. We describe an advanced, exportable method for imaging the pancreatic inflammation underlying T1D, based on MRI of the clinically approved magnetic nanoparticle (MNP) ferumoxytol. The MNP-MRI approach, which reflects nanoparticle uptake by macrophages in the inflamed pancreatic lesion, has been validated extensively in mouse models of T1D and in a pilot human study. The methodological advances reported here were enabled by extensive optimization of image acquisition at 3T, as well as by the development of improved MRI registration and visualization technologies. A proof-of-principle study on patients recently diagnosed with T1D versus healthy controls yielded two major findings: First, there was a clear difference in whole-pancreas nanoparticle accumulation in patients and controls; second, the patients with T1D exhibited pronounced inter- and intrapancreatic heterogeneity in signal intensity. The ability to generate noninvasive, 3D, high-resolution maps of pancreatic inflammation in autoimmune diabetes should prove invaluable in assessing disease initiation and progression and as an indicator of response to emerging therapies.

Reduced beta-cell reserve and pancreatic volume in survivors of childhood acute lymphoblastic leukaemia treated with bone marrow transplantation and total body irradiation

BACKGROUND

Impaired glucose tolerance (IGT) and diabetes mellitus (DM) occur more frequently after bone marrow transplantation and total body irradiation (BMT/TBI), but the mechanism is unclear. This study investigates insulin sensitivity, β-cell reserve and pancreatic volume in adult survivors of childhood acute lymphoblastic leukaemia (ALL).

METHOD

Survivors (aged 16-26 years) of ALL treated with BMT/TBI (10-14·4 Gy) Group 1 (n = 20, 10 m) were compared with a chemotherapy-only Group 2 (n = 28, 11 m). Participants underwent assessments of insulin sensitivity by whole body composite-insulin-sensitivity-index (ISIcomp ) from oral glucose tolerance tests (OGTTs); first (AIRarg , AIRg , AUCin10 ) and second (AUC in second phase ) phase insulin responses from arginine-intravenous glucose tolerance tests; and pancreatic volume by abdominal magnetic resonance imaging (MRI). Data were analysed by odds ratio, Chi-square or Fisher's exact tests, Student's t-tests, analysis of covariance (ancova) and Pearson's or partial correlations (5% significance).

RESULTS

Abnormal OGTTs were documented in Group 1 (DM = 2, IGT = 7). Insulin secretion adjusted for insulin sensitivity was lower in Group 1 than Group 2 as a whole [LogAIRarg (P = 0·008), logAIRg (P = 0·013) and logAUCin10 (P = 0·014)] and after exclusion of those with abnormal glucose tolerance [logAIRarg (P = 0·011), logAIRg (P = 0·007) and logAUCin10 (P = 0·006)]. Group 1 had lower pancreatic volume than Group 2 [52·0 (14·2) vs 72·8 (23·5), P = 0·001] cm(3) , and results were consistent after adjustment for size by body surface area (P = 0·019). Pancreatic volume correlated with logAIRarg adjusted log ISIcomp (partial correlation = 0·34, P = 0·025).

CONCLUSIONS

Adult survivors of childhood BMT/TBI for ALL demonstrated reduced β-cell reserve and smaller pancreatic volume, both likely additional aetiological factors, with reduced insulin sensitivity, in their increased risk of diabetes.

Extra-pancreatic effects of incretin-based therapies

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion and inhibits glucagon secretion in the pancreatic islets of Langerhans under hyperglycaemia. In type 2 diabetes (T2DM), GLP-1 improves glycaemic control without a hypoglycaemia risk. GLP-1 receptors have also been found in extra-pancreatic tissues, e.g., the cardiovascular system, the gastrointestinal system, and the central nervous system. Since cardiovascular comorbidities and degenerative neurological changes are associated with T2DM, the interest in the extrapancreatic effects of GLP-1 has increased. GLP-1-based therapies with either GLP-1 receptor agonists (GLP-1 RA) or DPP-4 inhibitors (that delay the degradation of endogenous GLP-1) have become widely used therapeutic options in T2DM. In clinical studies, GLP-1 RA have demonstrated a significant lowering of blood pressure that is independent of body weight changes. Preclinical data and small short-term studies with GLP-1 and GLP-1 RA have shown cardioprotective effects in ischaemia models. GLP-1 as well as a treatment with GLP-1 RA also induces a stable body weight loss by affecting GLP-1 signaling in the hypothalamus and by slowing gastric emptying. Regarding neuroprotective actions in degenerative neurological disease models for Parkinson's- or Alzheimer's disease or neurovascular complications like stroke, animal studies have shown positive results. In this article, a summary of the extrapancreatic effects of GLP-1 and GLP-1-based therapies is presented.

The extra-pancreatic effects of GLP-1 receptor agonists: a focus on the cardiovascular, gastrointestinal and central nervous systems

The glucagon-like peptide-1 receptor agonists (GLP-1RAs) exenatide, liraglutide and lixisenatide have been shown to improve glycaemic control and beta-cell function with a low risk of hypoglycaemia in people with type 2 diabetes. GLP-1 receptors are also expressed in extra-pancreatic tissues and trial data suggest that GLP-1RAs also have effects beyond their glycaemic actions. Preclinical studies using native GLP-1 or GLP-1RAs provide substantial evidence for cardioprotective effects, while clinical trial data have shown beneficial actions on hypertension and dyslipidaemia in people with type 2 diabetes. Significant weight loss has been reported with GLP-1RAs in both people with type 2 diabetes and obese people without diabetes. GLP-1RAs also slow down gastric emptying, but preclinical data suggest that the main mechanism behind GLP-1RA-induced weight loss is more likely to involve their effects on appetite signalling in the brain. GLP-1RAs have also been shown to exert a neuroprotective role in rodent models of stroke, Alzheimer's disease and Parkinson's disease. These extra-pancreatic effects of GLP-1RAs could provide multi-factorial benefits to people with type 2 diabetes. Potential adverse effects of GLP-1RA treatment are usually manageable but may include gastrointestinal effects, increased heart rate and renal injury. While extensive further research is still required, early data suggest that GLP-1RAs may also have the potential to favourably impact cardiovascular disease, obesity or neurological disorders in people without diabetes in the future.

Pancreas volume measurement in patients with Type 2 diabetes using magnetic resonance imaging-based planimetry

BACKGROUND/OBJECTIVES

To compare pancreas volume (PV) measurement using MRI-based planimetry in patients with Type 2 diabetes mellitus (DM) to PV in normoglycemic individuals.

METHODS

Our institutional review board granted approval of this retrospective study with waiver of informed consent. We searched 2296 consecutive abdominal MRI studies performed at our hospital on patients with no pancreas pathology between September 1, 2010 and February 28, 2013, for those who also had a fasting plasma glucose and/or hemoglobin A1C within six months of the MRI examination. For those patients who met biochemical criteria for DM, we used medication and clinical records to confirm that 32 of these patients had Type 2 DM. The pancreas contours of 32 Type 2 diabetics and 50 normoglycemic individuals were then traced on non-gadolinium T1-weighted 3D fat suppressed gradient echo images by a radiologist trained in abdominal MRI to calculate PV. PV index (PVI) was calculated as PV/weight to adjust PV for each patient's weight. PVs and PVIs in both cohorts were compared using t-tests and regression models correcting for weight, age and gender.

RESULTS

Patients with Type 2 DM had significantly lower PVs than normoglycemic individuals (72.7 ± 20.7 cm(3) versus 89.6 ± 22.7 cm(3), p < 0.001), and significantly lower PVIs (1.0 ± 0.3 cm(3)/kg versus 1.3 ± 0.3 cm(3)/kg, p < 0.001). Using regression models, we found that given the same age, weight and gender, the PV in a patient with Type 2 DM was 17.9 mL (20%) lower compared to a normoglycemic individual (p < 0.001).

CONCLUSION

PV is reduced in Type 2 DM compared to normoglycemic individuals and can be measured using MRI without contrast injection.

A non-invasive method of quantifying pancreatic volume in mice using micro-MRI

In experimental models of pancreatic growth and recovery, changes in pancreatic size are assessed by euthanizing a large cohort of animals at varying time points and measuring organ mass. However, to ascertain this information in clinical practice, patients with pancreatic disorders routinely undergo non-invasive cross-sectional imaging of the pancreas using magnetic resonance imaging (MRI) or computed tomography (CT). The aim of the current study was to develop a thin-sliced, optimized sequence protocol using a high field MRI to accurately calculate pancreatic volumes in the most common experimental animal, the mouse. Using a 7 Telsa Bruker micro-MRI system, we performed abdominal imaging in whole-fixed mice in three standard planes: axial, sagittal, and coronal. The contour of the pancreas was traced using Vitrea software and then transformed into a 3-dimensional (3D) reconstruction, from which volumetric measurements were calculated. Images were optimized using heart perfusion-fixation, T1 sequence analysis, and 0.2 to 0.4 mm thick slices. As proof of principle, increases in pancreatic volume among mice of different ages correlated tightly with increasing body weight. In summary, this is the first study to measure pancreatic volumes in mice, using a high field 7 Tesla micro-MRI and a thin-sliced, optimized sequence protocol. We anticipate that micro-MRI will improve the ability to non-invasively quantify changes in pancreatic size and will dramatically reduce the number of animals required to serially assess pancreatic growth and recovery.

Beta-cell imaging: call for evidence-based and scientific approach

INTRODUCTION

Advances in positron emission tomography (PET) imaging have provided opportunities to develop radiotracers specific for imaging insulin-producing pancreatic β-cells. However, a host of lingering questions should be addressed before these radiotracers are advocated for noninvasive quantification of β-cell mass (BCM) in vivo in the native pancreas.

METHOD

We provide an overview of tetrabenazine-based PET tracers developed to image and quantify BCM and discuss several theoretical, technical, and biological limitations of applying these tracers in clinical practice.

DISCUSSION

VMAT2, a transporter protein expressed on pancreatic β-cells, has been advocated as a promising target for PET imaging tracers, such as dihydrotetrabenazine. However, the lack of radiotracer specificity for these proteins hampers their clinical application. Another important argument against their use is a striking discrepancy between radiotracer uptake and BCM in subjects with type I diabetes mellitus and healthy controls. Additionally, technical issues, such as the finite spatial resolution of PET, partial volume effects, and movement of the pancreas during respiration, impede PET imaging as a viable option for BCM quantification in the foreseeable future.

CONCLUSION

The assertion that BCM can be accurately quantified by tetrabenazine derived β-cell-specific radiotracers as density per unit volume of pancreatic tissue is not justifiable at this time. The fallacy of these claims can be explained by technical as well as biological facts that have been disregarded and ignored in the literature.

Assessment of exocrine pancreatic function by secretin-stimulated magnetic resonance cholangiopancreaticography and diffusion-weighted imaging in healthy controls

PURPOSE

To characterize and quantify exocrine pancreatic function by secretin-stimulated magnetic resonance cholangiopancreaticography (s-MRCP) and diffusion-weighted imaging (DWI) in healthy subjects and compare these findings to morphological features, ie, pancreatic volume and secretin-stimulated peak bicarbonate concentration measured in pancreatic juice.

MATERIALS AND METHODS

Pancreatic magnetic resonance imaging (MRI) (1.5 T) was performed in 20 healthy volunteers among which 10 underwent gastroscopy with duodenal intubation. MRI included T2-weighted imaging and DWI acquired before and 1, 5, 9, and 13 minutes after secretin administration. Secreted pancreatic juice volumes were calculated based on the sequential T2-weighted images and pancreatic volumes and apparent diffusion coefficient (ADC) values were estimated.

RESULTS

The mean pancreatic secretion rate declined from 9.5 mL/min at 1-5 minutes (postsecretin) to 2.9 mL/min at 9-13 minutes. Pancreatic head ADC values significantly increased from baseline (1.29 × 10(-3) mm(2) /s) to 1 minute postsecretin (1.48 × 10(-3) mm(2) /s) (P = 0.003). Secreted pancreatic juice volume at 1 minute after secretin correlated positively with peak bicarbonate concentration (n = 10, P = 0.05).

CONCLUSION

Secretin-stimulated MRCP and DWI can characterize and quantify exocrine pancreatic function in healthy subjects. These imaging methods may prove relevant for patients with exocrine pancreatic dysfunction.

Measurement of pancreatic volume by abdominal MRI: a validation study

Objective

To develop abdominal magnetic resonance imaging (MRI) protocol to measure pancreatic volume in humans and to validate it in large animals.

Materials and Methods

We performed abdominal MRI in eight mini-pigs using a clinical 3T MRI system. We used consecutive parallel abdominal slices, covering the entire pancreas to calculate pancreatic volume. Following MRI, animals were sacrificed, the pancreas was removed, and the volume of the pancreas was measured by water displacement. We used the same MRI protocol to measure pancreatic volume in 21 humans. To assess reproducibility of in vivo measurement we repeated MRI pancreas volume evaluation within 24 hours in additional five humans.

Results

In mini-pigs the measurements of pancreatic volume by MRI and by water displacement were almost identical (R² = 0.9867; p<0.0001). In humans the average pancreas volume was 72.7+/−4.5 ml, range from 35.0 to 105.5 ml. This result is in strong agreement with results of previous large postmortem and computed tomography (CT) studies. Repeated measurements of pancreatic volume in humans were highly reproducible. Pancreatic volume measured in vivo was negatively correlated with age, body fat mass, pancreatic TG levels, and visceral fat mass.

Conclusions

These initial results are highly encouraging and our protocol for pancreatic volume estimation in vivo may prove useful in obesity research to follow in vivo changes of pancreatic volume and structure during time course of obesity and type 2 diabetes development.

Age-related volumetric changes in pancreas: a stereological study on computed tomography

PURPOSE

(1) To explore age-related changes in the volume of the pancreas on computed tomography (CT) images calculated by the method of Cavalieri. (2) To investigate the relationship between these changes and body mass index (BMI), gender, abdominal diameter, abdominal skinfold thickness.

METHODS

We retrospectively reviewed abdominal CT examinations of 272 adults between the ages of 20-88 years. There were seven groups of patients, with 40 patients (only ninth decade has 32 patients) for each decade.

RESULTS

Pancreatic volume (PV) was found to be 63.68 ± 15.08 cm(3) in females, 71.75 ± 15.99 cm(3) in males (mean value of both groups, 67.71 ± 16.03 cm(3)). Maximum value of PV was found in the fourth decade in females, males and also for mean of both groups (73.50, 84.21 and 78.85 cm(3), respectively). PV remained constant until ~60 years of age. Thereafter, it gradually decreased in both genders. There was a negative correlation between PV and age (p < 0.001, r: -0.473). We found positive correlation between PV and BMI, sagittal abdominal diameter (SAD), transverse abdominal diameter (TAD), anterior subcutaneous adipose tissue thicknesses (ASAT), posterior subcutaneous adipose tissue thicknesses (PSAT), bilateral subcutaneous adipose tissue thicknesses (BSAT).

CONCLUSIONS

Quantitative data may allow clinicians to better estimate age-related PV changes and help them in decision making.

In vivo imaging of endogenous pancreatic β-cell mass in healthy and type 1 diabetic subjects using 18F-fluoropropyl-dihydrotetrabenazine and PET

The ability to noninvasively measure endogenous pancreatic β-cell mass (BCM) would accelerate research on the pathophysiology of diabetes and revolutionize the preclinical development of new treatments, the clinical assessment of therapeutic efficacy, and the early diagnosis and subsequent monitoring of disease progression. The vesicular monoamine transporter type 2 (VMAT2) is coexpressed with insulin in β-cells and represents a promising target for BCM imaging.

METHODS

We evaluated the VMAT2 radiotracer (18)F-fluoropropyl-dihydrotetrabenazine ((18)F-FP-(+)-DTBZ, also known as (18)F-AV-133) for quantitative PET of BCM in healthy control subjects and patients with type 1 diabetes mellitus. Standardized uptake value was calculated as the net tracer uptake in the pancreas normalized by injected dose and body weight. Total volume of distribution, the equilibrium ratio of tracer concentration in tissue relative to plasma, was estimated by kinetic modeling with arterial input functions. Binding potential, the steady-state ratio of specific binding to nondisplaceable uptake, was calculated using the renal cortex as a reference tissue devoid of specific VMAT2 binding.

RESULTS

Mean pancreatic standardized uptake value, total volume of distribution, and binding potential were reduced by 38%, 20%, and 40%, respectively, in type 1 diabetes mellitus. The radiotracer binding parameters correlated with insulin secretion capacity as determined by arginine-stimulus tests. Group differences and correlations with β-cell function were enhanced for total pancreas binding parameters that accounted for tracer binding density and organ volume.

CONCLUSION

These findings demonstrate that quantitative evaluation of islet β-cell density and aggregate BCM can be performed clinically with (18)F-FP-(+)-DTBZ PET.

The role of pancreatic imaging in monogenic diabetes mellitus

In neonatal diabetes mellitus resulting from mutations in EIF2AK3, PTF1A, HNF1B, PDX1 or RFX6, pancreatic aplasia or hypoplasia is typical. In maturity-onset diabetes mellitus of the young (MODY), mutations in HNF1B result in aplasia of pancreatic body and tail, and mutations in CEL lead to lipomatosis. The pancreas is not readily accessible for histopathological investigations and pancreatic imaging might, therefore, prove important for diagnosis, treatment, and research into these β-cell diseases. Advanced imaging techniques can identify the pancreatic features that are characteristic of inherited diabetes subtypes, including alterations in organ size (diffuse atrophy and complete or partial pancreatic agenesis), lipomatosis and calcifications. Consequently, in patients with suspected monogenic diabetes mellitus, the results of pancreatic imaging could help guide the molecular and genetic investigation. Imaging findings also highlight the critical roles of specific genes in normal pancreatic development and differentiation and provide new insight into alterations in pancreatic structure that are relevant for β-cell disease.

Noninvasive imaging of pancreatic islet inflammation in type 1A diabetes patients

Type 1A diabetes (T1D) is an autoimmune disease characterized by leukocyte infiltration of the pancreatic islets of Langerhans. A major impediment to advances in understanding, preventing, and curing T1D has been the inability to "see" the disease initiate, progress, or regress, especially during the occult phase. Here, we report the development of a noninvasive method to visualize T1D at the target organ level in patients with active insulitis. Specifically, we visualized islet inflammation, manifest by microvascular changes and monocyte/macrophage recruitment and activation, using magnetic resonance imaging of magnetic nanoparticles (MNPs). As a proof of principle for this approach, imaging of infused ferumoxtran-10 nanoparticles permitted effective visualization of the pancreas and distinction of recent-onset diabetes patients from nondiabetic controls. The observation that MNPs accumulate in the pancreas of T1D patients opens the door to exploiting this noninvasive imaging method to follow T1D progression and monitoring the ability of immunomodulatory agents to clear insulitis.

MRI appearance of the pancreas in patients with cystic fibrosis: a comparison of pancreas volume in diabetic and non-diabetic patients

We investigated differences in the volume of the pancreas in cystic fibrosis (CF) patients with and without diabetes using MRI to study the natural history of CF-related diabetes (CFRD). We investigated 29 pancreas-insufficient adult CF patients, 13 with CFRD and 16 without diabetes. Patients with CFRD were receiving insulin therapy at the time of study. None of the non-diabetic CF patients had evidence of impaired glucose tolerance. Pancreas volume was estimated by MRI scans using T₁ weighted fat-suppression sequences and assessed by an examiner who was unaware of the patients' diabetes status. Pancreas volume of CF patients was measured and subsequently compared with that of non-CF age-matched Type 1 diabetes (T1DM) patients and healthy controls previously investigated. The two CF groups were matched for age and gender. There were no differences in spirometry values, body mass index or pancreatic exocrine function. The pancreas was visible by MRI in only 3 of 13 (23.1%) patients with CFRD and in 5 of 16 (31.3%) patients without diabetes (p-value = 0.7). In total, the pancreas was not detected by MRI as an anatomical entity in 21 of 29 (72.4%) CF patients, irrespective of their diabetes status. When comparing the four study groups, the pancreas was significantly smaller in CF patients than in T1DM patients and healthy controls.

The size of the spleen by magnetic resonance imaging in patients with cystic fibrosis; with and without diabetes--a novel observational study

BACKGROUND

Magnetic resonance imaging (MRI) has been shown to be a useful tool to evaluate the volume of the pancreas. There is currently no information about the size of the spleen in cystic fibrosis (CF) patients.

PATIENTS AND METHODS

We investigated 51 adult volunteers: 28 pancreatic insufficient CF patients [13 with CF-related diabetes (CFRD) and 15 non-diabetic] and 23 male non-CF patients [12 with type 1 diabetes mellitus (T1DM) and 11 healthy control subjects]. Patients with known liver cirrhosis or portal hypertension were excluded. The size of the spleen was measured in all subjects by an investigator unaware of patients' clinical status. For comparison of spleen size in the four study groups only male CF patients were included. For CF patients, spleen size was compared with forced expiratory volume in 1 s (FEV(1)), body mass index (BMI), total number of days of intravenous (IV) antibiotic treatment for pulmonary exacerbations in year previous to study, levels of circulating white blood cells, glycosylated haemoglobin A1c (HbA1c), and exocrine function of the pancreas, as assessed by daily requirement of oral lipase.

RESULTS

Amongst the four study groups, spleen size was greatest in the male non-diabetic CF patients (P = 0.01). For CF patients, spleen size was greater in male compared to female patients (P = 0.012). For patients with CFRD, there was an inverse correlation between the spleen size and HbA1c (r = -0.59, P = 0.04) and the daily intake of supplementary lipase (r = -0.63, P = 0.02). The size of the spleen in patients with CFRD, but not in CF patients without CFRD, inversely correlated with the days of IV antibiotic treatment received in the year previous to the study (r = -0.67, P = 0.012). There was no correlation between spleen size and BMI, FEV1 and white blood cell counts in any group.

CONCLUSION

On MRI, the spleen size was greatest in male non-diabetic CF patients in comparison with other groups. The size of the spleen in CFRD patients was smaller when diabetes was poorly controlled, when exocrine pancreatic function was greatly impaired and in those with greater need for IV antibiotics in the year prior to the study.

Review: The importance of residual endogenous beta-cell preservation in type 1 diabetes

Achieving tight glycaemic control in type 1 diabetes remains very challenging for patients. However, some individuals retain a degree of endogenous beta-cell function for 5 or more years after diagnosis, and prospective studies confirm that this is associated not only with lower glycated haemoglobin A1c levels, and less hypoglycaemia, but also a reduced incidence of long-term complications. An independent effect of insulin C-peptide may contribute to this beneficial effect. Retention of even small amounts of endogenous beta-cell function for as long as possible should therefore be a key therapeutic goal in type 1 diabetes. Tight glycaemic control from diagnosis has already been shown to help in this regard, and we argue that the introduction of novel immunotherapies which achieve this important goal should be strongly encouraged, even if they fall short of an insulin-free 'cure'.

11C-dihydrotetrabenazine PET of the pancreas in subjects with long-standing type 1 diabetes and in healthy controls

Type 2 vesicular monoamine transporter (VMAT2), found in the brain, is also expressed by beta-cells of the pancreas in association with insulin. Preclinical experiments suggested that (11)C-dihydrotetrabenazine PET-measured VMAT2 binding might serve as a biomarker of beta-cell mass. We evaluated the feasibility of (11)C-dihydrotetrabenazine PET quantification of pancreatic VMAT2 binding in healthy subjects and patients with long-standing type 1 diabetes.

METHODS

(11)C-Dihydrotetrabenazine PET was performed on 6 patients and 9 controls. VMAT2 binding potential (BP(ND)) was estimated voxelwise by using the renal cortex as reference tissue. As an index of total pancreatic VMAT2, the functional binding capacity (the sum of voxel BP(ND) x voxel volume) was calculated. Pancreatic BP(ND), functional binding capacity, and stimulated insulin secretion measurements were compared between groups.

RESULTS

The pancreatic mean BP(ND) was decreased in patients (1.86 +/- 0.05) to 86% of control values (2.14 +/- 0.08) (P = 0.01). In controls, but not in patients, BP(ND) correlated with stimulated insulin secretion (r(2) = 0.50, P = 0.03). The average functional binding capacity was decreased by at least 40% in patients (P = 0.001). The changes in functional binding capacity and BP(ND) were less than the near-complete loss of stimulated insulin secretion observed in patients (P = 0.001).

CONCLUSION

These results suggest that (11)C-dihydrotetrabenazine PET allows quantification of VMAT2 binding in the human pancreas. However, BP(ND) and functional binding capacity appear to overestimate beta-cell mass given the near-complete depletion of beta-cell mass in long-standing type 1 diabetes, which may be due to higher nonspecific binding in the pancreas than in the renal cortex.

Reduced pancreatic volume in hepatocyte nuclear factor 1A-maturity-onset diabetes of the young

CONTEXT

There are interplays between the endocrine and exocrine pancreas. We recently reported an increased frequency of exocrine dysfunction in HNF1A-maturity-onset diabetes of the young (MODY3) patients, compared with controls. Reduced pancreatic volume is seen in HNF1B-MODY (MODY5) and diabetes types 1 and 2.

OBJECTIVE

The aim of this study was to investigate whether HNF1A mutation carriers have reduced pancreatic volume or abnormal pancreatic structure and whether any changes are associated with exocrine dysfunction.

METHODS

Fifteen HNF1A mutation carriers recruited from the Norwegian MODY Registry, 31 subjects with type 1 diabetes, 10 subjects with type 2 diabetes, and 11 controls underwent computed tomography of the pancreas. We measured pancreatic volume and X-ray attenuation. Pancreatic volume index was defined as pancreatic volume divided by body surface area.

RESULTS

Pancreatic volume index was reduced in subjects with HNF1A-MODY (34.5 ml/m2; P < 0.02) and type 1 diabetes (21.4 ml/m2; P < 0.001) as compared with nondiabetic controls (45.7 ml/m2), and was reduced in subjects with diabetes in combination with fecal elastase deficiency (P = 0.03). Subjects with type 1 diabetes had smaller pancreatic volume index, compared with HNF1A mutation carriers (P < 0.001). Reduced pancreatic volume index was associated with increasing duration of diabetes. Pancreatic X-ray attenuation in HNF1A mutation carriers was not significantly different from that of nondiabetic controls.

CONCLUSIONS

HNF1A mutation carriers have reduced pancreatic volume but less reduced than in patients with type 1 diabetes. Insulinopenia could explain both the pancreatic volume reduction and the associated pancreatic dysfunction.

Pancreas volumes in humans from birth to age one hundred taking into account sex, obesity, and presence of type-2 diabetes

Our aims were (1) by computed tomography (CT) to establish a population database for pancreas volume (parenchyma and fat) from birth to age 100 years, (2) in adults, to establish the impact of gender, obesity, and the presence or absence of type-2 diabetes on pancreatic volume (parenchyma and fat), and (3) to confirm the latter histologically from pancreatic tissue obtained at autopsy with a particular emphasis on whether pancreatic fat is increased in type-2 diabetes. We measured pancreas volume in 135 children and 1,886 adults (1,721 nondiabetic and 165 with type-2 diabetes) with no history of pancreas disease who had undergone abdominal CT scan between 2003 and 2006. Pancreas volume was computed from the contour of the pancreas on each CT image. In addition to total pancreas volume, parenchymal volume, fat volume, and fat/parenchyma ratio (F/P ratio) were determined by CT density. We also quantified pancreatic fat in autopsy tissue of 47 adults (24 nondiabetic and 23 with type-2 diabetes). During childhood and adolescence, the volumes of total pancreas, pancreatic parenchyma, and fat increase linearly with age. From age 20–60 years, pancreas volume reaches a plateau (72.4 ± 25.8 cm³ total; 44.5 ± 16.5 cm³ parenchyma) and then declines thereafter. In adults, total (∼32%), parenchymal (∼13%), and fat (∼68%) volumes increase with obesity. Pancreatic fat content also increases with aging but is not further increased in type-2 diabetes. We provide lifelong population data for total pancreatic, parenchymal, and fat volumes in humans. Although pancreatic fat increases with aging and obesity, it is not increased in type-2 diabetes. Clin. Anat. 20:933–942, 2007. © 2007 Wiley-Liss, Inc.