Imaging of Gaucher disease

Deep learning-based quantification of osteonecrosis using magnetic resonance images in Gaucher disease

Gaucher disease is one of the most common lysosomal storage disorders. Osteonecrosis is a principal clinical manifestation of Gaucher disease and often leads to joint collapse and fractures. T1-weighted (T1w) modality in MRI is widely used to monitor bone involvement in Gaucher disease and to diagnose osteonecrosis. However, objective and quantitative methods for characterizing osteonecrosis are still limited. In this work, we present a deep learning-based quantification approach for the segmentation of osteonecrosis and the extraction of characteristic parameters. We first constructed two independent U-net models to segment the osteonecrosis and bone marrow unaffected by osteonecrosis (UBM) in spine and femur respectively, based on T1w images from patients in the UK national Gaucherite study database. We manually delineated parcellation maps including osteonecrosis and UBM from 364 T1w images (176 for spine, 188 for femur) as the training datasets, and the trained models were subsequently applied to all the 917 T1w images in the database. To quantify the segmentation, we calculated morphological parameters including the volume of osteonecrosis, the volume of UBM, and the fraction of total marrow occupied by osteonecrosis. Then, we examined the correlation between calculated features and the bone marrow burden score for marrow infiltration of the corresponding image, and no strong correlation was found. In addition, we analyzed the influence of splenectomy and the interval between the age at first symptom and the age of onset of treatment on the quantitative measurements of osteonecrosis. The results are consistent with previous studies, showing that prior splenectomy is closely associated with the fractional volume of osteonecrosis, and there is a positive relationship between the duration of untreated disease and the quantifications of osteonecrosis. We propose this technique as an efficient and reliable tool for assessing the extent of osteonecrosis in MR images of patients and improving prediction of clinically important adverse events.

Machine Learning-Driven Biomarker Discovery for Skeletal Complications in Type 1 Gaucher Disease Patients

Type 1 Gaucher disease (GD1) is a rare, autosomal recessive disorder caused by glucocerebrosidase deficiency. Skeletal manifestations represent one of the most debilitating and potentially irreversible complications of GD1. Although imaging studies are the gold standard, early diagnostic/prognostic tools, such as molecular biomarkers, are needed for the rapid management of skeletal complications. This study aimed to identify potential protein biomarkers capable of predicting the early diagnosis of bone skeletal complications in GD1 patients using artificial intelligence. An in silico study was performed using the novel Therapeutic Performance Mapping System methodology to construct mathematical models of GD1-associated complications at the protein level. Pathophysiological characterization was performed before modeling, and a data science strategy was applied to the predicted protein activity for each protein in the models to identify classifiers. Statistical criteria were used to prioritize the most promising candidates, and 18 candidates were identified. Among them, PDGFB, IL1R2, PTH and CCL3 (MIP-1α) were highlighted due to their ease of measurement in blood. This study proposes a validated novel tool to discover new protein biomarkers to support clinician decision-making in an area where medical needs have not yet been met. However, confirming the results using in vitro and/or in vivo studies is necessary.

Skeletal Manifestations of Gaucher's Disease: A Case Report and Literature Review

Gaucher's disease (GD) is a lysosomal storage disorder characterized by the storage of glucosylceramide in macrophages ("Gaucher cells"), mainly in the reticuloendothelial system. GD type 1 (GD1) is the most common phenotype that usually manifests with hepatosplenomegaly, cytopenias, and bone involvement. Skeletal manifestations are the most debilitating characteristic and result in significant morbidities. We describe a case of GD1, first presented by a nontraumatic bone fracture. The case presentation highlights the importance of considering GD among the differential diagnosis of nontraumatic fractures, avascular necrosis, and infarcts of the bones. Early diagnosis and treatment improve the course of disease and avoid irreversible sequelae.

Pictorial review: challenges in distinguishing bilateral metaphyseal marrow abnormalities on magnetic resonance imaging

The paediatric metaphysis is afflicted by a wide range of pathological processes as it is the most metabolically active and well-vascularised part of the developing skeleton. This review focuses on metaphyseal marrow signal change detected with magnetic resonance imaging, which is most often occult on radiographs. When bilateral, these imaging appearances frequently present a diagnostic quandary. This review assists the radiologist to confidently dismiss physiological signal change and confidently work through the differential diagnosis. This is achieved by illustrating a practical method of classifying signal change into four categories: physiological red marrow, red marrow reconversion, marrow infiltration, and oedema-like marrow signal intensity. In doing so, various pathological entities are reviewed along with imaging pearls and next-step investigations.

Fat fraction quantification of bone marrow in the lumbar spine using the LiverLab assessment tool in healthy adult volunteers and patients with Gaucher disease

BACKGROUND

Magnetic Resonance Imaging is used for evaluation of bone in Gaucher disease (GD), but a widely available quantitative scoring method remains elusive.

AIMS

The study purpose was to assess the reproducibility of the LiverLab tool for assessing bone marrow fat fraction (FF) and determine whether it could differentiate GD patients from healthy subjects.

METHODS

Ten healthy volunteers and 18 GD patients were prospectively recruited. FF was calculated at L3, L4 and L5. GD patient bone marrow burden (BMB) score assessed by one observer. Inter and intra-rater agreement assessed with Bland-Altman data plots. Differences in FF between healthy volunteers versus GD patients and between subjects treated versus not treated assessed using two-sample t-tests. In GD patients, the relationship between FF, BMB and glucosylsphingosine was determined using the Pearson's correlation coefficient.

RESULTS

Healthy volunteer mean FF was 0.36, standard deviation (SD) 0.10 (range 0.20-0.57). Intra and inter-rater SD were both 0.02. GD patient mean FF was 0.40, SD 0.13 (range 0.09-0.57). No statistical difference was shown between healthy volunteers and GD patients (P = 0.447) or between GD patients whether on enzyme replacement therapy or not (P = 0.090). No significant correlation between mean FF and total BMB (r = -0.525, P = 0.253) or between FF and glucosylsphingosine levels (r = 0.287, P = 0.248).

CONCLUSION

Excellent reproducibility of LiverLab FF measurements across studies and observers is comparable to Dixon quantitative chemical shift imaging (QCSI). Lack of statistical difference between GD patients and controls may be explained by limited patient numbers, active treatment or mild disease severity in untreated patients.

Gaucher Disease: An Unusual Cause of Knee Pain

INTRODUCTION

Gaucher disease (GD) is a genetic lysosomal disorder leading to storage of the glycolipid molecule glucocerebroside in macrophages, causing multiorgan dysfunction. Bone marrow involvement may result in painful bone crisis and hematologic disturbance.

CASE REPORT

We present a case of a 13-year-old adolescent boy with right knee pain. Radiograph and magnetic resonance imaging of the distal femur indicated possible osteomyelitis or bone tumor. However, histologic examination of bone biopsy material suggested the diagnosis of GD, which was confirmed by detection of decreased β-glucocerebrosidase activity and identification of the exact gene mutation.

DISCUSSION

Many visceral and bone abnormalities of GD have been described. The diagnosis of GD is based on clinical and laboratory findings and is established by the measurement of β-glucocerebrosidase dysfunction and the study of GBA gene mutations. Treatment is currently based on enzyme replacement and substrate reduction.

CONCLUSION

This is a rare case of GD presenting initially with knee pain. Because early diagnosis is important for the treatment of this condition, orthopaedic surgeons should consider this uncommon cause in the differential diagnosis of joint pain.

Neuronopathic Gaucher disease: Beyond lysosomal dysfunction

Gaucher disease (GD) is an inherited disorder caused by recessive mutations in the GBA1 gene that encodes the lysosomal enzyme β-glucocerebrosidase (β-GC). β-GC hydrolyzes glucosylceramide (GluCer) into glucose and ceramide in the lysosome, and the loss of its activity leads to GluCer accumulation in different tissues. In severe cases, enzymatic deficiency triggers inflammation, organomegaly, bone disease, and neurodegeneration. Neuronopathic Gaucher disease (nGD) encompasses two different forms of the disease, characterized by chronic or acute damage to the central nervous system (CNS). The cellular and molecular studies that uncover the pathological mechanisms of nGD mainly focus on lysosomal dysfunction since the lysosome is the key organelle affected in GD. However, new studies show alterations in other organelles that contribute to nGD pathology. For instance, abnormal accumulation of GluCer in lysosomes due to the loss of β-GC activity leads to excessive calcium release from the endoplasmic reticulum (ER), activating the ER-associated degradation pathway and the unfolded protein response. Recent evidence indicates mitophagy is altered in nGD, resulting in the accumulation of dysfunctional mitochondria, a critical factor in disease progression. Additionally, nGD patients present alterations in mitochondrial morphology, membrane potential, ATP production, and increased reactive oxygen species (ROS) levels. Little is known about potential dysfunction in other organelles of the secretory pathway, such as the Golgi apparatus and exosomes. This review focuses on collecting evidence regarding organelle dysfunction beyond lysosomes in nGD. We briefly describe cellular and animal models and signaling pathways relevant to uncovering the pathological mechanisms and new therapeutic targets in GD.

Pearls and Pitfalls of Imaging of the Developing Pediatric Skeleton: Differentiating Normal and Pathology With MRI

Developmental changes occurring in the pediatric skeleton throughout childhood cause imaging appearances that may be confused with pathology. Knowledge of the typical pattern of red to yellow bone marrow conversion and areas of normal developmental irregular ossification is essential for radiologists interpreting musculoskeletal imaging in children to avoid mistaking normal findings for disease. Here we review the normal conversion of hematopoietic to yellow marrow on pediatric MRI and illustrate how MRI can distinguish the normal areas of irregular ossification from various pathology that can occur at and around growth centers in the developing skeleton.

Targeting neurological abnormalities in lysosomal storage diseases

Central nervous system (CNS) abnormalities and corresponding neurological and psychiatric symptoms are frequently observed in lysosomal storage disorders (LSDs). The genetic background of individual LSDs is indeed unique to each illness. However, resulting defective lysosomal function within the CNS can transition normal cellular processes (i.e., autophagy) into aberrant mechanisms, facilitating overlapping downstream consequences including neurocircuitry dysfunction, neurodegeneration as well as sensory, motor, cognitive, and psychological symptoms. Here, the neurological and biobehavioral phenotypes of major classes of LSDs are discussed alongside therapeutic strategies in development that aim to tackle neuropathology among other disease elements. Finally, focused ultrasound blood-brain barrier opening is proposed to enhance therapeutic delivery thereby overcoming the key hurdle of central distribution of disease modifying therapies in LSDs.

Hepatosplenomegaly in liver cirrhosis is caused by reactive oxygen species formation, an increase in apoptosis and autophagy, and pronounced autoimmune reactions

Various factors of infectious and toxic genesis can lead to the liver cirrhosis, often accompanied by complications such as recurrent bleeding due to portal hypertension against the background of hepatosplenomegaly. Metabolic changes and disturbances in immunoreactivity occur in the liver and spleen. To substantiate the choice of personalized treatment tactics for patients with hepatosplenomegaly, we investigated individual metabolic predictors and immunopathological processes in patients with: liver cirrhosis and hepatitis B (HBV) and/or hepatitis C (HCV) viruses (I group, n = 52); with herpes viruses CMV (cytomegalovirus) and EBV (Epstein-Barr virus) (II group, n = 48), and with splenomegaly and frequent recurrent bleeding associated with hereditary enzymopathies (III group, n = 15). We used the methods of immunoturbidimetry; enzyme immunoassay; light, fluorescence and confocal microscopy. In group I (HBV/HCV), we revealed a decrease in the C4 component; a significant increase in the phagocytic index and phagocytic number, a reduced number of active phagocytes and the digestion index; a decrease in the IL-1β content and an increase in IL-18 and IL-6. In group II (CMV/EBV), we revealed a high activity of the C3 and a low activity of the C4 component against the background of a high level of ROS in neutrophils; the antineutrophil antibodies (ANCA) formation in 85.7% of patients (71.4% –perinuclear antibodies (pANCA) to myeloperoxidase; 14.3% – cytoplasmic antibodies (CANCA) to proteinase 3). Also, in group II, an increased level of pro-inflammatory cytokines IFN-γ, IL-1β, TNF-α, IL-18 and anti-inflammatory IL-6 was detected. Changes in links of immunity in II group led to the formation of autoimmune reactions in 64.7% of patients, which was expressed in the development of a broad range of antinuclear antibodies ANA (11 specificities, including ANA to chromatin and chromatin-associated proteins, to proteins cytoskeleton, enzymes and enzyme complexes). In group III, we revealed a low absorption capacity of neutrophils, a high frequency of antineutrophil antibodies pANCA occurrence and cANCA (in 67.2% of the examined), and low concentration of TNF-α. The developed model of the stepwise change of immunological markers makes it possible to substantiate the choice of a complex targeted treatment, including antiviral and immunotropic therapy.

"Flip-Flop Phenomenon" - Magnetic Resonance Imaging Pitfall: A Case Report

A 66-year-old cachectic female with underlying anorexia nervosa and lower limb weakness was referred for a spinal Magnetic Resonance Imaging. Imaging appearances were initially thought to represent underlying systemic pathology involving bone marrow or inadvertent wrong selection of imaging sequences. It was, however, established that unique imaging appearances are secondary to 'Flip-Flop' phenomenon owing to underlying nutritional status of the patient. 'Flip-Flop' phenomenon on the Magnetic Resonance Imaging is result of an underlying pathological process of serous atrophy of bone marrow. Appreciation and recognition of this phenomenon will help in the correct interpretation of the images and leads a clinician toward appropriate management.

99mTc-MDP Bone Scintigraphy in Gaucher Disease

In this case report, we present the bone scintigraphic findings of a 9-year-old boy with Gaucher disease who has a history of fractures to evaluate the extent of his osseous lesions. Gaucher disease is a genetic deficiency of lysosomal enzyme glucocerebrosidase, which results in the accumulation of glucocerebroside in the macrophages in the reticuloendothelial cells of the spleen, liver, and bone marrow. Most patients with type 1 Gaucher disease present a clinical or radiographic evidence of infiltrative bone disease. Lipid-filled macrophages called Gaucher cells infiltrate the bone marrow, leading to medullary expansion, diffuse osteoporosis, ischemic necrosis, and fractures.

Gaucher disease status and treatment assessment: pilot study using magnetic resonance spectroscopy bone marrow fat fractions in pediatric patients

OBJECTIVE

To assess magnetic resonance spectroscopy (MRS) bone marrow fat fractions' ability to discern between untreated Gaucher disease patients and healthy controls based on assessment of bone marrow infiltration and evaluate response to enzyme replacement therapy (ERT) on serial imaging.

METHODS

This retrospective case-controlled study compared conventional MRI and bone marrow MRS findings in six pediatric and young adult Gaucher disease patients with age- and sex-matched controls, examining femoral neck and lumbar spine bone marrow fat fractions and bone marrow burden (BMB) scores. Separate analysis of six patients with serial imaging on ERT was performed with analysis of fat fractions, BMB scores, organ volumes, and serum chitotriosidase.

RESULTS

Untreated patients had significantly lower femoral and lumbar spine fat fractions than controls (0.32 versus 0.67, p = 0.041 and 0.17 versus 0.34, p = 0.041, respectively). Total BMB scores were significantly higher in patients (8.0 versus 3.5, p = 0.015). In patients on ERT with average follow-up of 3.5 years, femoral neck fat fraction was the sole significant predictor of treatment duration (R square: 0.804, p < 0.001) when adjusted for age. Femoral neck fat fraction also correlated with lumbar spine fat fraction, liver volume and chitotriosidase (p < 0.05). MRS test-retest reliability was excellent (Pearson correlations: 0.96, 0.99; p-values <0.001). BMB inter-rater reliability was good overall with an intra-class correlation coefficient of 0.79 for total score, although lumbar spine score reliability was poor at 0.45.

CONCLUSION

MRS-derived bone marrow fat fractions appear capable of detecting Gaucher disease severity and monitoring treatment-related changes as a predictor of ERT duration in pediatric and young adult patients.

Imaging of non-neuronopathic Gaucher disease: recent advances in quantitative imaging and comprehensive assessment of disease involvement

Gaucher disease is an inherited metabolic disorder resulting in deficiency of lysosomal enzyme β-glucocerebrosidase causing the accumulation of abnormal macrophages (“Gaucher cells”) within multiple organs, most conspicuously affecting the liver, spleen, and bone marrow. As the most common glycolipid metabolism disorder, it is important for radiologists encountering these patients to be familiar with advances in imaging of organ and bone marrow involvement and understand the role of imaging in clinical decision-making. The recent advent of commercially available, reliable, and reproducible quantitative MRI acquisitions to measure fat fractions prompts revisiting the role of quantitative assessment of bone marrow involvement. This manuscript reviews the diverse imaging manifestations of Gaucher disease and discusses more optimal quantitative approaches to ascertain solid organ and bone marrow involvement with an emphasis on future applications of other quantitative methods including elastography.

Population-based cohort of 500 patients with Gaucher disease in Israel

OBJECTIVE

To characterise a population-based cohort of patients with Gaucher disease (GD) in Israel relative to the general population and describe sociodemographic and clinical differences by disease severity (ie, enzyme replacement therapy [ERT] use).

DESIGN

A cross-sectional study was conducted.

SETTING

Data from the Clalit Health Services electronic health record (EHR) database were used.

PARTICIPANTS

The study population included all patients in the Clalit EHR database identified as having GD as of 30 June 2014.

RESULTS

A total of 500 patients with GD were identified and assessed. The majority were ≥18 years of age (90.6%), female (54.0%), Jewish (93.6%) and 34.8% had high socioeconomic status, compared with 19.0% in the general Clalit population. Over half of patients with GD with available data (51.0%) were overweight/obese and 63.5% had a Charlson Comorbidity Index ≥1, compared with 46.6% and 30.4%, respectively, in the general Clalit population. The majority of patients with GD had a history of anaemia (69.6%) or thrombocytopaenia (62.0%), 40.4% had a history of bone events and 22.2% had a history of cancer. Overall, 41.2% had received ERT.

CONCLUSIONS

Establishing a population-based cohort of patients with GD is essential to understanding disease progression and management. In this study, we highlight the need for physicians to monitor patients with GD regardless of their ERT status.

Splenomegaly: A Combined Clinical and Radiologic Approach to the Differential Diagnosis

An enlarged spleen (splenomegaly) is a common imaging finding and may be related to a broad array of underlying conditions. The multifaceted functions of the spleen make it susceptible to involvement by a variety of pathophysiologic processes. Understanding these conditions and incorporating all relevant clinical and radiologic data allow narrowing the differential diagnosis.

Actual reason for bone fractures in the case of a patient followed-up with the osteogenesis imperfecta: Gaucher's Disease

Gaucher's disease (GD) is a rare disease characterized by a β-glucocerebroside accumulation in the reticulo-endothelial system. Patients may refer to the clinic with complaints of bone pain, hepatosplenomegaly, anemia, thrombocytopenia, growth retardation, interstitial pulmonary disease, pulmonary hypertension, and skeletal disorders. Skeletal system involvement is observed commonly in Gaucher patients and a significant cause of morbidity. Our patient was followed for several years as a glass child - osteogenesis imperfecta and he had joint deformities due to skeletal fractures. We wanted to present this case to raise awareness of GD's skeletal involvement and effects of late diagnosis.

Benign Bone Conditions That May Be FDG-avid and Mimic Malignancy

Positron emission tomography with the radiotracer ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) plays an important role in the evaluation of bone pathology. However, FDG is not a cancer-specific agent, and knowledge of the differential diagnosis of benign FDG-avid bone alterations that may resemble malignancy is important for correct patient management, including the avoidance of unnecessary additional invasive tests such as bone biopsy. This review summarizes and illustrates the spectrum of benign bone conditions that may be FDG-avid and mimic malignancy, including osteomyelitis, bone lesions due to benign systemic diseases (Brown tumor, Erdheim-Chester disease, Gaucher disease, gout and other types of arthritis, Langerhans cell histiocytosis, and sarcoidosis), benign primary bone lesions (bone cysts, chondroblastoma, chondromyxoid fibroma, desmoplastic fibroma, enchondroma, giant cell tumor and granuloma, hemangioma, nonossifying fibroma, and osteoid osteoma and osteoblastoma), and a group of miscellaneous benign bone conditions (post bone marrow biopsy or harvest status, bone marrow hyperplasia, fibrous dysplasia, fractures, osteonecrosis, Paget disease of bone, particle disease, and Schmorl nodes). Several ancillary clinical and imaging findings may be helpful in discriminating benign from malignant FDG-avid bone lesions. However, this distinction is sometimes difficult or even impossible, and tissue acquisition will be required to establish the final diagnosis.

Gaucher disease in the liver on hepatocyte specific contrast agent enhanced MR imaging

Gaucher disease is a hereditary lipid storage disorder that affects the enzyme beta glucocerebrosidase, causing accumulation of glucocerebroside in macrophages of the reticuloendothelial system. Accumulation can occur in the liver and spleen, manifesting as hepatosplenomegaly, as well as within the bone marrow. Hepatic involvement is usually diffuse but can occasionally manifest as focal liver lesions. We present a case of a 2-year-old boy with Gaucher disease and an infiltrating liver lesion detected on imaging, which was pathologically shown to be focal changes related to the disease. Imaging characteristics of this lesion using hepatocyte specific contrast agent enhanced MRI, which have not been previously discussed in the literature, are described.

The radiology of diffuse interstitial pulmonary disease in children: pearls, pitfalls and new kids on the block in 2015

Diffuse interstitial lung disease in children differs markedly from interstitial lung disease in adults and is a distinct entity. The childhood interstitial lung disease (ChILD) classification, devised in 2010 separates conditions into those occurring in infancy, and those not specific to infants, the later group containing many conditions related to systemic diseases (including connective tissue diseases and depositional/storage disorders), and conditions occurring in immunocompromised children. In this article, we briefly review normal lung growth and development. We discuss our preferred technique for imaging the lungs with computed tomography in children, and review the recent literature regarding the radiological appearance of various ChILD. We illustrate this with cases from our institution and emphasize the more recently recognised conditions including pleuroparenchymal fibroelastosis and filamin A deficiency-related lung disease.

Mucopolysaccharidosis-like phenotype in feline Sandhoff disease and partial correction after AAV gene therapy

Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme β-N-acetylhexosaminidase. Children with infantile onset SD develop seizures, loss of motor tone and swallowing problems, eventually reaching a vegetative state with death typically by 4years of age. Other symptoms include vertebral gibbus and cardiac abnormalities strikingly similar to those of the mucopolysaccharidoses. Isolated fibroblasts from SD patients have impaired catabolism of glycosaminoglycans (GAGs). To evaluate mucopolysaccharidosis-like features of the feline SD model, we utilized radiography, MRI, echocardiography, histopathology and GAG quantification of both central nervous system and peripheral tissues/fluids. The feline SD model exhibits cardiac valvular and structural abnormalities, skeletal changes and spinal cord compression that are consistent with accumulation of GAGs, but are much less prominent than the severe neurologic disease that defines the humane endpoint (4.5±0.5months). Sixteen weeks after intracranial AAV gene therapy, GAG storage was cleared in the SD cat cerebral cortex and liver, but not in the heart, lung, skeletal muscle, kidney, spleen, pancreas, small intestine, skin, or urine. GAG storage worsens with time and therefore may become a significant source of pathology in humans whose lives are substantially lengthened by gene therapy or other novel treatments for the primary, neurologic disease.