Multi-parametric MR imaging using apparent diffusion coefficient and fat fraction in quantification of bone marrow in pediatrics with Gaucher disease

Challenges in Gaucher disease: Perspectives from an expert panel

This focused review concentrates on eight topics of high importance for Gaucher disease (GD) clinicians and researchers: 1) The consideration of GD as distinct types rather than a spectrum. A review of the literature clearly supports the view that there are distinct types of GD. Type 1 is characterized by the absence of primary neuronopathic involvement, while types 2 and 3 are characterized by progressive primary neuronopathic disease. 2) Neurologic and neuronopathic manifestations. A growing body of evidence indicates that the peripheral nervous system may be involved in GD type 1 and that there may also be signs and symptoms of central nervous system (CNS) disease in this group. However, GD type 1 is characterized by the absence of primary neuronopathic disease, whereas GD types 2 and 3 are characterized by progressive, albeit variable, primary neuronopathic disease. Abnormalities in saccadic eye movements have been suggested as being diagnostic for neuronopathic GD, but they may also occur in GD type 1 and in other inflammatory diseases. 3) The importance of whole GBA1 sequencing. This approach is superior to exome sequencing because of potential effects of deep intronic variants on gene expression. It also has the capacity to detect variant alleles that might be missed with gene panels. 4) Monoclonal gammopathy of undetermined significance (MGUS). The risks of MGUS, multiple myeloma, and non-Hodgkin's lymphoma are elevated in patients with GD compared to the general population and strong evidence indicates that lyso-Gb1 stimulates the formation of monoclonal immunoglobulins (M-protein) in patients with GD and MGUS. 5) Pulmonary involvement in GD. Pulmonary complications can be identified through spirometry in up to 45 % of patients with GD type 1 and 55 % of those with GD type 3. Limited evidence exists that enzyme replacement therapy (ERT) reduces the severity of these complications in patients with GD type 1. 6) Gaucheromas. These may occur in patients with GD types 1 or 3, but there is little detailed information about their inception, mechanisms underlying growth, cellular organization, and biochemical activities, and no definitive guidance for their management. Gaucheromas behave like benign (i.e. non-metastasizing) neoplasms, and it may be reasonable to classify them as such. 7) Bone and joint involvement. Dual-energy X-ray absorptiometry scans alone are insufficient for monitoring all changes in bone that may occur in patients with GD. Quantitative magnetic resonance imaging (MRI) techniques using Dixon quantitative chemical shift imaging have provided results that correlate with GD severity scores, bone complications, and biomarkers for GD bone involvement. Thoracic kyphosis is a common complication of GD types 1 and 3, and there is very limited information regarding the effects of ERT or substrate synthesis inhibition therapy (SSIT) on this condition. 8) Treatment initiation, selection, combination, and switching. Prompt initiation of treatment in pediatric patients is important as GD can lead to impaired growth, lower peak bone mass, and delayed puberty. These adverse outcomes can often be ameliorated or prevented with timely treatment. Either ERT or eliglustat, a SSIT agent, is suitable as first-line treatment of adults with GD. Studies of switching from ERT to eliglustat, or between different ERT products, have indicated that changing treatment is safe, although efficacy outcomes vary. A critical remaining issue is the lack of treatments capable of reaching the CNS to slow or halt the progression of neuronopathic disease in patients with GD type 2 or 3 and potentially reduce the risk of Parkinson's disease in GD type 1 patients and heterozygotes for GBA1 variants.

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.

Chronic Stress and Steatosis of Muscles, Bones, Liver, and Pancreas: A Review

BACKGROUND

Chronic stress is a recognized risk factor for poor health, body composition disequilibrium, impaired mental health, and deterioration of quality of life. Chronic stress-related cortisol oversecretion and circadian dysregulation and associated systemic low grade, injurious inflammation ("para-inflammation") contribute to steatosis in various metabolically active solid organs, affecting both their structure and function. The aim of this review was to summarize current knowledge on the impact of chronic stress and associated para-inflammation on skeletal muscle, bone, liver, and pancreas, leading to their steatosis. Current management of these maladaptive conditions is also included and underscored in this review.

SUMMARY

Steatosis of metabolically active solid organs is involved in various metabolic processes and considered a risk factor for chronic noncommunicable diseases, yet its role in chronic stress physiology and pathophysiology has been overlooked.

KEY MESSAGES

Chronic stress-associated steatosis of several solid organs is generally disregarded in current clinical practice. Physicians should be alert for these steatoses and should address them adequately so as to provide appropriate medical care. New guidelines generated by learned societies are needed, along with large observational studies, to offer novel solutions to this old problem.

Pre- and post-therapeutic evaluation of liver and spleen in type I and type III Gaucher's disease using diffusion tensor imaging

PURPOSE

To assess the role of diffusion tensor imaging in assessing liver and splenic parenchymal infiltration in Gaucher's disease (G.D.) type I and III before and after therapy.

METHODS

A prospective study was conducted upon 28 consecutive patients with G.D. type I and III and 28 age and sex-matched controls. They underwent an MRI and DTI of the liver and spleen. Mean diffusivity (M.D.) and fractional anisotropy (F.A.) values of the liver and spleen were evaluated before and after treatment and compared with control.

RESULTS

There was a statistically significant difference in the M.D. value of the liver and spleen between untreated patients and controls and between control and treated patients and in the M.D. value of the liver and spleen between untreated and treated patients. There is a statistically significant difference in the F.A. value of the liver and spleen between untreated patients and controls and in the F.A. value of the liver and spleen between untreated and treated patients. Hemoglobin level was positively correlated with the M.D. value of the spleen. Clinical score was negatively correlated with M.D. value of the spleen and was positively correlated with F.A. values of the liver and F.A. values of the spleen. Spleen volume was negatively correlated with M.D. values of the spleen.

CONCLUSION

Significant difference in M.D. and F.A. values of liver and splenic parenchyma in p atients with type I and III G.D. and controls, and between untreated and treated patients. The M.D. and F.A. values were well correlated with some biomarkers of disease activity.

Diffusion tensor imaging of vertebral bone marrow in children with Gaucher's disease type I and III: Pre- and post-therapy

PURPOSE

To assess diffusion tensor imaging (DTI) of the vertebral bone marrow (BM) in children with Gaucher's disease (GD) types I and III before and after therapy.

METHODS

Prospective study was conducted upon 25 children with GD type I (n = 17) and III (n = 8) and 13 age and sex-matched controls underwent DTI of vertebral BM. Mean diffusivity (MD) and fractional anisotropy (FA) of vertebral BM was calculated and correlated with genotyping, chitotriosidase, hemoglobin (HB) and, platelet count.

RESULTS

There was a statistically significant difference in MD and FA of BM between patients and controls (P = 0.001 and 0.02). The area under the curve (AUC) of MD and FA used to differentiate untreated patients from controls was 0.902 and 0.68 with sensitivity, specificity, and, accuracy 92%, 84.6%, and, 89.5% respectively. There was a significant difference in MD and FA of BM between untreated and treated patients (P = 0.001 and 0.02). AUC of MD and FA used to differentiate untreated from treated patients was 0.93 and 0.649 with sensitivity, specificity, and accuracy of 92%, 80%, and 86% respectively. There was a significant difference in MD and FA (P = 0.03, 0.001 respectively) of BM in GD with homozygous L444P mutation (n = 9) and other mutations (n = 14). Chiotriptase, HB and platelet count of patients was correlated with MD (r = -0.36, 0.42, -0.41) and FA (r = -0.47, -0.37, -0.46) respectively.

CONCLUSION

DTI of vertebral BM can help in diagnosis and monitoring patients with GD after therapy and correlated with genotyping, and hematological biomarkers of GD.

Bone marrow fat change in pediatric patients with non-alcoholic fatty liver disease

OBJECTIVES

To investigate changes of fat in bone marrow (BM) and paraspinal muscle (PSM) associated with the degree of fatty liver in pediatric patients with non-alcoholic fatty liver disease (NAFLD) in consideration of age and body mass index (BMI).

METHODS

Hepatic fat, BM fat, and PSM fat from proton density fat fraction of liver MRI between June 2015 and April 2019 were quantitatively evaluated on axial images of the fat map at the mid-level of T11-L2 vertebral bodies for BM fat and at the mid-level of L2 for PSM fat. Age, height, and weight at the time of MRI were recorded and BMI was calculated. Correlation analysis was performed.

RESULTS

A total of 147 patients (114 male) were included with a mean age of 13.3 ± 2.9 years (range 7-18 years). The mean fat fractions were 24.3 ± 13.0% (2-53%) in liver, 37.4 ± 8.6% (17.3-56%) in vertebral BM, and 2.7 ± 1.1% (1.0-6.9%) in PSM. Age, height, weight, and BMI were not correlated with liver fat or BM fat. However, weight (ρ = 0.174, p = 0.035) and BMI (ρ = 0.247, p = 0.003) were positively correlated with PSM fat. Liver fat showed positive correlation with BM fat when adjusting age and BMI (ρ = 0.309, p<0.001), but not with PSM fat.

CONCLUSIONS

BM fat positively correlates with liver fat, but not with age or BMI in pediatric NAFLD patients.

Clinical and Genetic Varieties of Gaucher Disease in Iraqi Children

Gaucher disease (GD), which is due to a deficiency in the lysosomal enzyme β-glucocerebrosidase, is a rare genetic disorder. It is characterized by a wide variety of clinical manifestations and severity of symptoms, making it difficult to manage. A cross-sectional hospital-based genetic study was undertaken with 32 pediatric patients. We recruited 21 males and 11 females diagnosed with GD, with a male-to-female ratio of 1.91:1. The mean age of the study population was 8.79 ± 4.37 years with an age range from 8 months to 17 years. We included patients on clinical evaluation from 2011 to 2019. An enzyme assay test was used to measure β-glucosidase enzyme activity in leukocytes and the GBA gene study was performed by polymerase chain reaction technique. We found GD type 1 in 27 (84.37%) participants, GD type 3 in five (15.63%) participants, while none classified as GD type 2. The dominant mutation in GD 1 was N370S in 81.5%, of which two-thirds were homozygous. The second common mutation in this type of disease (L444P) was present in nine cases (40.9%), two of whom were homozygous (9.9%). Meanwhile, R463C was present in six cases (27.27%), of whom one was homozygous. In GD 3, the dominant mutation was L444P as seen in 80% of the patients followed by N370S and R463C in 20%. This study shows that the most common mutant allele in this study was N370S, followed by L444P. Further large-scale studies with more advanced designs are recommended to explore the sequences of GBA genes.

Pharmacological treatment of pediatric Gaucher disease

INTRODUCTION

Gaucher disease (GD) is an autosomal recessive disorder resulting from the deficiency of the lysosomal enzyme glucocerebrosidase (b-glucosidase), associated with varying degrees of visceral, bone and central nervous system pathology, leading to wide phenotypic diversity. Response to therapy and clinical outcomes are very different between the three clinical subtypes - non-neuronopathic, acute neuronopathic, and chronic neuronopathic forms; hence a definitive clinical diagnosis is essential. The availability of two therapeutic options, i.e. enzyme replacement and substrate reduction, has transformed the natural course of the disease. As pre-treatment disease severity clearly impacts results of therapy, early diagnosis and initiation of treatment especially in the pediatric population are keys to achieving an optimal outcome. Areas covered: We reviewed the literature concerning the treatment of GD focusing on pediatric presentations, various pharmacological treatment options and recommendations for management goals. A PubMed literature search was performed for relevant publications between 1991 and September 2018. Expert commentary: The approval of enzyme replacement therapy (ERT) for GD in the pediatric age group has significantly altered the course of the disease, especially for non-neuronopathic and chronic neuronopathic forms, as ERT does not cross the blood-brain barrier. Early diagnosis, regular follow-up and early initiation of treatment can thus prevent some irreversible complications and improve patient quality of life.

Risk factors associated with clinical adjacent segment pathology following multi-level cervical fusion surgery

Few clinical studies investigate risk factors associated with clinical adjacent segment pathology (CASP) following multi-level cervical fusion surgery. The aim is to record the incidence of postoperative CASP in patients after at least 2 years' follow-up and to identify possible risk factors that may be associated with the CASP after multi-level cervical surgery.We retrospectively reviewed patients who underwent multi-level cervical surgery in our hospital from January 2004 to February 2016. All patients underwent more than 2 years' follow-up. The diagnosis of CASP is according to clinical symptoms as well as image findings. Potential risk factors were collected from demographic data and radiographic images.A total of 301 patients after multi-level cervical surgery were analyzed. During follow-up, 28 patients (9.3%) were diagnosed as having CASP. Among these patients, 7 showed symptoms of CASP within 3 years after surgery, 6 showed symptoms between 3 and 5 years, 14 showed symptoms between 5 and 10 years, and the last one showed symptoms more than 10 years later. In the multivariate analysis, degeneration of adjacent segment (OR, 1.592; 95% CI, 1.113-2.277), decreased Cobb angle in fused vertebrae (OR, 2.113; 95% CI, 1.338-3.334) and decreased Cobb angle in cervical spine (OR, 1.896; 95% CI, 1.246-2.886) were correlated with the incidence of CASP during follow-up.The incidence of CASP following multi-level cervical surgery was 9.3% with a mean of about 70 months' follow-up. Patients with preoperative degeneration of adjacent segment and postoperative imbalance of sagittal alignment have a higher risk of developing CASP after multi-level cervical surgery.

Acute Gaucher Disease-Like Condition in an Indian Infant with a Novel Biallelic Mutation in the Prosaposin Gene

This is the first reported case of prosaposin ( PSAP ) mutation from India manifesting as an acute neuronal Gaucher disease-like condition. A 2-month-old male baby presented with encephalopathy, resistant tonic-clonic seizures, moderate hepatosplenomegaly, hypotonia, and cherry red spot in the retinae. The child had anemia, thrombocytopenia, elevated chitotriosidase, and normal activity of acid sphingomyelinase and low normal activity of β-glucosidase 1 (β-glucocerebrosidase 1, GBA). The child succumbed in the fourth month of life due to persistent respiratory distress and refractory seizures. The clinical phenotype, cherry red spots, elevated chitotriosidase, and lysosomal assays led to the suspicion of Gaucher disease. Exome sequencing revealed a homozygous stop codon mutation in the PSAP gene (c.G1228T, p.Glu410ter). Prenatal diagnosis in the next pregnancy revealed a carrier fetus, who was unaffected postnatally. The diagnosis of specific activator deficiency such as saposin C and saposin D deficiency (in the current study) should be considered and tested for when Gaucher disease is suspected in an infant with partially deficient or near normal GBA activity.