Dialysis-related amyloidosis revisited

Multisystem Imaging Manifestations of Kidney Failure

Kidney failure (KF) refers to a progressive decline in glomerular filtration rate to below 15 ml/min per 1.73 m2, necessitating renal replacement therapy with dialysis or renal transplant. The hemodynamic and metabolic alterations in KF combined with a proinflammatory and coagulopathic state leads to complex multisystemic complications. The imaging hallmark of systemic manifestations of KF is bone resorption caused by secondary hyperparathyroidism. Other musculoskeletal complications include brown tumor, osteosclerosis, calcinosis, soft-tissue calcification, and amyloid arthropathy. Cardiovascular complications and infections are the leading causes of death in KF. Cardiovascular complications include accelerated atherosclerosis, cardiomyopathy, pericarditis, myocardial calcinosis, and venous thromboembolism. Neurologic complications such as encephalopathy, osmotic demyelination, cerebrovascular disease, and opportunistic infections are also frequently encountered. Pulmonary complications include edema and calcifications. Radiography and CT are used in assessing musculoskeletal and thoracic complications, while MRI plays a key role in assessing neurologic and cardiovascular complications. CT iodinated contrast material is generally avoided in patients with KF except in situations where the benefit of contrast-enhanced CT outweighs the risks and in patients already undergoing maintenance dialysis. At MRI, group II gadolinium-based contrast material can be safely administered in patients with KF. The authors discuss the extrarenal systemic manifestations of KF, the choice of imaging modality in their assessment, and imaging findings of complications. ©RSNA, 2024 Supplemental material is available for this article.

Elevated concentration of beta2-microglobulin among patients with carpal tunnel syndrome in the course of primary Sjögren syndrome - a prospective observational study on 50 patients

INTRODUCTION

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltrates in the exocrine glands. Carpal tunnel syndrome (CTS) is suggested to be more frequent among SS patients than in the general population. The aim of this study was to seek associations between the CTS and the laboratory and clinical findings of SS patients.

METHODS

Fifty patients diagnosed with primary SS (pSS) were examined. Clinical evaluation by a rheumatologist and electrophysiological studies were conducted. Data on laboratory tests results was collected. Control group consisted of 50 sex and age-matched individuals with osteoarthritis (OA).

RESULTS

Out of 50 patients in the study group 27 (54%) were diagnosed with CTS. The prevalence of CTS among 50 individuals in the control group was 8%. Among pSS patients with CTS the joint involvement was not more common than in those from the non-CTS group [15 vs. 13 (p = 0.945)]. There was an expected difference in sleep disorders [18 vs. 9 (p = 0.012)] and paresthesia [23 vs. 13 (p = 0.024)]. The major finding was a significant difference in elevated beta2-microglobulin (B2MG) [23 vs. 13 (p = 0.024)]. Other studied factors, suggested in the literature as significant in the pSS-related neuropathy, were not statistically different between the groups.

CONCLUSION

Our study confirms that CTS is more prevalent among pSS patients than in the general population and suggests that a new approach is required towards the pathogenesis of this phenomenon. We hypothesize that CTS is more associated with an overall disease activity than joint involvement as such.

Elevated intraneural vascularization of the median nerve proximal to the arteriovenous fistula in hemodialysis patients suspected of carpal tunnel syndrome: A case series

Patients with end-stage kidney disease may require creation of an arteriovenous fistula in order to receive hemodialysis treatment. The creation may result in several complications, including carpal tunnel syndrome. Early diagnosis and treatment are essential to relieve symptoms, prevent permanent nerve damage, and improve quality of life. However, the sensory and motor disturbances resembling carpal tunnel syndrome could be related to other etiologies than external compression of the median nerve underneath the transverse ligament. This case report presents eight patients with a radiocephalic arteriovenous fistula, who all had symptoms of carpal tunnel syndrome. Ultrasonographic examination showed a segmental intraneural hypervascularization of a large vessel inside the median nerve proximal to the wrist and arteriovenous fistula anastomosis with garland-like course as well as multiple flow velocities. The neurophysiological findings showed a significant decreased velocity in the ipsilateral forearm to the arteriovenous fistula.

Articular Findings on Chest Computed Tomography: An Algorithmic Approach for Radiologists

ABSTRACT

Chest computed tomography (CT) is one of the most frequently performed imaging studies. Incidental osseous and articular findings are commonly encountered in chest CTs in daily practice. The spectrum of findings is broad, varying from benign to malignant, and interpretation of these incidental musculoskeletal findings could be challenging for radiologists. In this review, we provide a systematic algorithmic approach for the diagnosis of common articular findings seen on chest CT with recommendations for appropriate follow-up evaluation.

Imaging of Spine Infections

The incidence of spondylodiskitis has increased over the last 20 years worldwide, especially in the immunodepressed population, and it remains a complex pathology, both in terms of diagnosis and treatment. Because clinical symptoms are often nonspecific and blood culture negative, imaging plays an essential role in the diagnostic process. Magnetic resonance imaging, in particular, is the gold standard technique because it can show essential findings such as vertebral bone marrow, disk signal alteration, a paravertebral or epidural abscess, and, in the advanced stage of disease, fusion or collapse of the vertebral elements. However, many noninfectious spine diseases can simulate spinal infection. In this article, we present imaging features of specific infectious spine diseases that help radiologists make the distinction between infectious and noninfectious processes.

Ultrasonographic assessment of entheseal sites of upper and lower extremities in hemodialysis patients using Madrid Sonography Enthesitis Index

Background

There is no much information about the entheseal involvement among hemodialysis (HD) patients. The aim of this study was to assess the frequency and distribution of ultrasonographic (US) entheseal alterations in HD patients and to evaluate the association between US abnormalities and both clinical and laboratory data.

Methods

This study was conducted on 41 HD patients and 23 sex- and age- matched controls. All participants were evaluated clinically for any signs of enthesopathy. Six entheses sites were scanned bilaterally using grey scale (GS) and power Doppler (PD) US and were scored using Madrid Sonography Enthesitis Index (MASEI) scoring system.

Results

In HD patients, at least one clinical sign suggestive of enthesopathy was found in 69 (14%) of 492 entheses. HD patients had statistically significant higher scores of structural tendon abnormalities (p < 0.001), enthesis thickening (p < 0.001), bone erosions (p < 0.001) and calcification (p = 0.037) than the healthy controls. Total MASEI score was higher in HD patients than healthy controls (median;18 vs 8, p < 0.001), also, MASEI-inflammatory (median;11 vs 3, p < 0.001) and damage scores (median;6 vs 0, p < 0.001). There was a statistically significant positive association between total MASEI score and both age (p = 0.032) and duration of HD (p = 0.037). Duration of HD was predictive for both MASEI-damage component (p = 0.004) and total MASEI score (p = 0.014).

Conclusion

There is a high prevalence of subclinical enthesopathy in HD patients. The entheseal US alterations is much higher in HD patients than in healthy subjects. The duration of HD is the significant predictor of enthesopathy in HD patients.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. ¹⁸F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, ¹⁸F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as ¹⁸F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

The Use of Imaging Techniques in Chronic Kidney Disease-Mineral and Bone Disorders (CKD-MBD)-A Systematic Review

Although frequently silent, mineral and bone disease (MBD) is one of the most precocious complication of chronic kidney disease (CKD) and is omnipresent in patients with CKD stage 5. Its pathophysiology is complex, but basically, disturbances in vitamin D, phosphate, and calcium metabolism lead to a diverse range of clinical manifestations with secondary hyperparathyroidism usually being the most frequent. With the decline in renal function, CKD-MBD may induce microstructural changes in bone, vascular system and soft tissues, which results in macrostructural lesions, such as low bone mineral density (BMD) resulting in skeletal fractures, vascular and soft tissue calcifications. Moreover, low BMD, fractures, and vascular calcifications are linked with increased risk of cardiovascular mortality and all-cause mortality. Therefore, a better characterization of CKD-MBD patterns, beyond biochemical markers, is helpful to adapt therapies and monitor strategies as used in the general population. An in-depth characterization of bone health is required, which includes an evaluation of cortical and trabecular bone structure and density and the degree of bone remodeling through bone biomarkers. Standard radiological imaging is generally used for the diagnosis of fracture or pseudo-fractures, vascular calcifications and other features of CKD-MBD. However, bone fractures can also be diagnosed using computed tomography (CT) scan, magnetic resonance (MR) imaging and vertebral fracture assessment (VFA). Fracture risk can be predicted by bone densitometry using dual-energy X-ray absorptiometry (DXA), quantitative computed tomography (QTC) and peripheral quantitative computed tomography (pQTC), quantitative ultrasound (QUS) and most recently magnetic resonance micro-imaging. Quantitative methods to assess bone consistency and strength complete the study and adjust the clinical management when integrated with clinical factors. The aim of this review is to provide a brief and comprehensive update of imaging techniques available for the diagnosis, prevention, treatment and monitoring of CKD-MBD.

Amyloidoma: a review and case report

Amyloidoma is a solitary mass of amyloid protein that arises in patients with or without evidence of systemic amyloidosis, and can be found in a variety of different organ systems. Herein, we describe three cases of localized biopsy-positive amyloidomas with no evidence of systemic involvement-primary amyloidoma. Our cases include a patient with a paraspinal soft tissue amyloidoma, a patient with multiple primary amyloidomas involving the thoracic cavity and flank, and a patient with insulin-injection induced amyloidoma of the left shoulder. We present these cases to provide further insights into the clinical presentation of this uncommon clinical entity. We review the pathophysiology of amyloidosis and discuss our cases in the context of previous reports of amyloidoma.

Shoulder Tumor/Tumor-Like Lesions: What to Look for

This article discusses the most common tumor and tumor-like lesions arising at the shoulder. Osseous tumors of the shoulder rank second in incidence to those at the knee joint and include benign osteochondromas and myeloma or primary malignant lesions, such as osteosarcoma or chondrosarcomas. Soft tissue tumors are overwhelmingly benign, with lipomas predominating, although malignant lesions, such as liposarcomas, can occur. Numerous tumor-like lesions may arise from the joints or bursae, due to either underlying arthropathy and synovitis (eg, rheumatoid arthritis and amyloid) or related to conditions, including tenosynovial giant cell tumor and synovial osteochondromatosis.

The Early Phase of β2-Microglobulin Aggregation: Perspectives From Molecular Simulations

Protein β2-microglobulin is the causing agent of two amyloidosis, dialysis related amyloidosis (DRA), affecting the bones and cartilages of individuals with chronic renal failure undergoing long-term hemodialysis, and a systemic amyloidosis, found in one French family, which impairs visceral organs. The protein’s small size and its biomedical significance attracted the attention of theoretical scientists, and there are now several studies addressing its aggregation mechanism in the context of molecular simulations. Here, we review the early phase of β2-microglobulin aggregation, by focusing on the identification and structural characterization of monomers with the ability to trigger aggregation, and initial small oligomers (dimers, tetramers, hexamers etc.) formed in the so-called nucleation phase. We focus our analysis on results from molecular simulations and integrate our views with those coming from in vitro experiments to provide a broader perspective of this interesting field of research. We also outline directions for future computer simulation studies.

Sternoclavicular Amyloid Arthropathy in a Patient With End-Stage Renal Disease

Amyloidosis is an extracellular deposition of amyloid located in different organs or in a systemic distribution. We present a case of a 78 year-old male with hemodyalisis assosciated amyloidosisis involving the right sternoclavicular joint. Clinical and imaging implications are described.

Mimickers of Hill-Sachs Lesions [Formula: see text]

The purpose of this article is to describe the imaging appearance, etiology, clinical features, and treatment of rare presentations of common bone and joint diseases known to mimic Hill-Sachs lesions. Knowledge of uncommonly encountered manifestations of ankylosing spondylitis, rheumatoid arthritis, septic joint, hyperparathyroidism, hydroxyapatite deposition disease, malignant bone tumors, and benign bone cysts which mimic traumatic Hill-Sachs lesions is important for radiologists to guide the clinical care of patients who present with shoulder symptoms.

Amyloidosis: diagnosis and new therapies for a misunderstood and misdiagnosed disease

Amyloidosis is a group of diseases characterized by extracellular deposition of amyloid fibril complexes. Fibril deposition results in organ dysfunction and possible failure. Amyloidosis is regarded as a rare disease, but in general is underdiagnosed. The two main types of systemic amyloidosis are immunoglobulin light chain and transthyretin amyloidosis. The increased availability of noninvasive cardiac imaging, genetic testing and improved laboratory assays and protein identification methods have led to increased diagnosis. However, in many cases, the diagnosis is not made until the patient develops organ impairment. Earlier diagnosis is required to prevent irreversible organ failure. Novel treatments for immunoglobulin light chain and transthyretin amyloidosis that halt disease progression, prolong and increase quality of life have recently become available.

Positron Emission Tomography Can Support the Diagnosis of Dialysis-Related Amyloidosis

BACKGROUND

The improvements in dialysis have not eliminated long-term problems, including dialysis-related amyloidosis (DRA), caused by Beta-2 microglobulin deposition. Several types of scintigraphy have been tested to detect DRA, none entered the clinical practice. Aim of the study was to assess the potential of PET-FDG scan in the diagnosis of DRA.

METHODS

Forty-six dialysis patients with at least one PET scan (72 scans) were selected out 162 patients treated in 2016-2018. Subjective global assessment (SGA), malnutrition inflammation score (A), Charlson Comorbidity Index (CCI), were assessed at time of scan; 218 age-matched cases with normal kidney function were selected as controls. PET scans were read in duplicate. Carpal tunnel syndrome was considered a proxy for DRA. A composite "amyloid score" score considered each dialysis year = 1 point; carpal tunnel-DRA = 5 points per site. Logistic regression, ROC curves and a prediction model were built.

RESULTS

The prevalence of positive PET was 43.5% in dialysis, 5% in controls (p < 0.0001). PET was positive in 14/15 (93.3%) scans in patients with carpal tunnel. PET sensitivity for detecting DRA was 95% (specificity 64%). Carpal tunnel was related to dialysis vintage and MIS. A positive PET scan was significantly associated with dialysis vintage, MIS and amyloid score. A prediction model to explain PET positivity combined clinical score and MIS, allowing for an AUC of 0.906 (CI: 0.813-0.962; p < 0.001).

CONCLUSIONS

PET-FDG may identify DRA, and may be useful in detecting cases in which inflammation favours B2M deposition. This finding, needing large-scale confirmation, could open new perspectives in the study of DRA.

Progression of dialysis-related amyloidoma towards pathologic fracture

Amyloidosis is the extracellular deposition of amyloid protein fibrils, and this condition may be hereditary or acquired. Patients undergoing long-term hemodialysis are particularly at risk for developing acquired amyloidosis. A rare form of amyloidosis is an amyloidoma or amyloid tumor, which occurs when amyloid focally deposits in a section of the musculoskeletal system, most commonly in the osteoarticular system. Here, we present a case of a hemodialysis-related amyloidoma of the left femoral neck in an 80-year-old woman with end-stage renal disease on hemodialysis for 8 years. The purpose of this report is to provide an account of the unique clinical, imaging, and histopathologic manifestation of a dialysis-related amyloidoma that progressively enlarges over a 2-year period. This report also highlights some prophylactic measures that may reduce the risk of developing an associated pathologic fracture.

Spinal Manifestations of Systemic Disease

The spine is frequently involved in systemic diseases, including those with neuropathic, infectious, inflammatory, rheumatologic, metabolic, and neoplastic etiologies. This article provides an overview of systemic disorders that may affect the spine, which can be subdivided into disorders predominantly involving the musculoskeletal system (including bones, joints, disks, muscles, and tendons) versus those predominantly involving the nervous system. By identifying the predominant pattern of spine involvement, a succinct, appropriate differential diagnosis can be generated. The importance of reviewing the medical record, as well as prior medical imaging (including nonspine imaging), which may confer greater specificity to the differential diagnosis, is stressed.

Radiologic Findings in Polyarticular Amyloid Arthropathy and Myopathy in Multiple Myeloma: A Case Report

Patient: Male, 56

Final Diagnosis: Amyloid arthropathy and myopathy

Symptoms: Polyarthralgia

Medication: —

Clinical Procedure: —

Specialty: Radiology

Multifocal metastatic chordoma to the soft tissues of the fingertips: a case report including sonographic features and a review of the literature

Chordoma is a rare, locally aggressive tumor which commonly metastasizes, most often to the lung, liver, and spine. In this case report, a 59-year-old male with history of sacral chordoma and pulmonary metastases presented to the emergency department with swelling and discoloration of multiple left fingertips. The initial radiographs led to a presumptive diagnosis of gout, which did not respond to medical therapy. An ultrasound demonstrated multiple solid masses with vascular hyperechoic septations which were subsequently biopsied and proven to be metastatic chordoma. Metastatic disease to the hand is a well documented but rare manifestation of many malignancies. The clinical presentation and radiographic features of multifocal hand metastases may mimic entities such as systemic deposition and granulomatous diseases. To the best of our knowledge, this is the first case report of soft tissue chordoma metastases to the fingertips as well as the first reported sonographic description of chordoma metastases.

Imaging characteristics of subcutaneous amyloid deposits in diabetic patients: the "insulin ball"

OBJECTIVE

The purpose of this study was to describe the imaging characteristics of subcutaneous amyloid deposits occurring at sites of insulin injection, commonly known as "insulin balls," in diabetic patients on ultrasound, CT, and MRI with pathologic correlation.

MATERIALS AND METHODS

We retrospectively reviewed the radiographic findings of 14 lesions in 9 patients diagnosed with subcutaneous amyloid deposits at our institution between 2005-2015. Three board-certified radiologists analyzed the following: (1) the shape, size, margin, morphologic characteristics, and blood flow on US using the color Doppler signal, (2) shape, size, margin, attenuation, and presence or absence of contrast enhancement on CT, and (3) shape, size, margin, signal intensity, and presence or absence of contrast enhancement on MRI.

RESULTS

All lesions showed ill-defined hypovascular subcutaneous nodules with irregular margins. The median diameter of lesions was 50.4 mm on US, 46.8 mm on CT, and 51.4 mm on MRI. The internal echogenicity of subcutaneous amyloid deposits was hypoechoic and heterogeneous on US. All lesions showed isodensity compared to muscle with irregular margins and minimal contrast enhancement on CT. Both T1- and T2-weighted MR images showed low signal intensity compared with subcutaneous fat. Normal diffusion and minimal contrast enhancement were seen.

CONCLUSIONS

Subcutaneous amyloid deposits which cause insulin resistance are typically ill-defined and heterogeneous hypovascular subcutaneous nodules with irregular margins on imaging that correspond to insulin injection sites. It is also characteristic that T2WI shows low intensity compared with fat on MRI, reflective of the amyloid content.

Persistent fever and destructive arthritis caused by dialysis-related amyloidosis: A case report

RATIONALE

Dialysis-related amyloidosis (DRA) can present rheumatic manifestations in patients on long-term hemodialysis. Typical articular symptoms with DRA involve carpal-tunnel syndrome, effusion in large joints, spondyloarthropathy, or cystic bone lesions, which are usually with non-inflammatory processes.

PATIENT CONCERNS

A 64-year-old man on hemodialysis for >30 years was admitted because of intermittent fever, polyarthritis, and elevated serum C-reactive protein (CRP) level, which was continuous for 2 years. Several antibiotics were ineffective for 3 months before his admission. On physical examination, joint swelling was observed at bilateral wrists, knees, ankles, and hip joints. Laboratory tests revealed elevation of serum inflammatory markers and β2-microglobulin (β2-MG). Synovial fluid showed predominant infiltration of polymorphonuclear leukocytes and the increase of β2-MG level.

DIAGNOSIS

Significant deposition of β2-MG with inflammatory cell infiltration was found in biopsied samples from synovium, skin, and ileum.

INTERVENTIONS

We decided to switch to the hemodialysis column with membrane that can effectively absorb β2-MG in circulation.

OUTCOMES

The relief of symptoms and a decrease of CRP level by changing the membrane lead to the final diagnosis of DRA.

LESSONS

Our case demonstrates that DRA arthropathy can be inflammatory and destructive, and also develop systemic inflammatory signs and symptoms. In such cases, aggressive absorption of β2-MG in circulation might help the amelioration of symptoms.

The unresolved problem of beta-2 microglobulin amyloid deposits in the intervertebral discs of long-term dialysis patients

BACKGROUND

Dialysis-related destructive spondyloarthropathy caused by beta-2 microglobulin (β2M) amyloid deposits in intervertebral discs is a major burden for patients undergoing long-term dialysis. This study aimed to quantify the presence of β2M amyloid deposits in the intervertebral disc tissue of such patients and analyze whether there was a significant correlation between β2M accumulation and the duration of dialysis.

METHODS

Two groups of patients who had undergone surgery for degenerative spinal pathologies were selected: the dialysis group (n = 29) with long-term dialysis and the control group (n = 10) with no renal impairment. Tissue sections were prepared from specimens of intervertebral disc tissue obtained during spinal surgery and analyzed via histological staining, including immunohistochemistry (IHC) and Congo red.

RESULTS

There was a statistically significant multifold increase of β2M expression in the disc tissue of long-term dialysis patients when compared to non-dialysis patients, as shown by both IHC (0.019 ± 0.023 μm² vs. 0.00020 ± 0.00033 μm², respectively; p = 0.012) and Congo red staining (0.027 ± 0.041 μm² vs. 9.240 × 10^-5 ± 5.261 × 10^-5 μm², respectively; p = 0.047). We also note a moderate strength positive correlation between the duration of dialysis and positive IHC (r = 0.39; p = 0.015) and Congo-red staining (r = 0.42; p = 0.007).

CONCLUSIONS

The problem of β2M amyloidosis in long-term dialysis patients remains unresolved even with predominant use of high-flux dialysis membranes. This highlights the insufficiency of current dialysis modalities to effectively filter β2M.

Ultrasound evaluation of bursae: anatomy and pathological appearances

A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.

Spectrum of Benign Articular and Periarticular Findings at FDG PET/CT

Whole-body fluorine 18 fluorodeoxyglucose (FDG) positron-emission tomography (PET)/computed tomography (CT) is performed primarily for oncologic indications; however, FDG uptake is not specific for malignancy. Herein we focus on causes of increased FDG uptake in and around joints, as lesions in these locations are commonly benign. A combination of primary intra-articular processes and osseous processes that may occur near the joint space will be discussed. Causes of intra-articular and periarticular increased FDG activity can be broadly divided into infectious, inflammatory, degenerative, and benign neoplastic categories. A familiarity with the full range of these processes is important to avoid misinterpretation, in turn decreasing unnecessary follow-up studies, procedures, and treatments. Differentiation from malignancy is often possible on the basis of a different level of FDG activity, divergent response to therapy, or differing changes over time, in comparison with a patient's known primary cancer. Recognizing an intra-articular lesion location can also be critical, as intra-articular metastases are rare. In some cases, benign FDG-avid articular and periarticular entities have a specific appearance at FDG PET/CT and a correct diagnosis may be made without any additional workup. In most other cases, comparison with prior studies and/or additional imaging can afford an accurate diagnosis. This review is meant to introduce the reader to a spectrum of benign FDG-avid articular and periarticular processes that may be encountered at oncologic FDG PET/CT to increase confidence and diagnostic accuracy. (©)RSNA, 2016.

Dialysis-related amyloidosis: challenges and solutions

Amyloidosis refers to the extracellular tissue deposition of fibrils composed of low-molecular-weight subunits of a variety of proteins. These deposits may result in a wide range of clinical manifestations depending upon their type, location, and the amount of deposition. Dialysis-related amyloidosis is a serious complication of long-term dialysis therapy and is characterized by the deposition of amyloid fibrils, principally composed of β2 microglobulins (β2M), in the osteoarticular structures and viscera. Most of the β2M is eliminated through glomerular filtration and subsequent reabsorption and catabolism by the proximal tubules. As a consequence, the serum levels of β2M are inversely related to the glomerular filtration rate; therefore, in end-stage renal disease patients, β2M levels increase up to 60-fold. Serum levels of β2M are also elevated in several pathological conditions such as chronic inflammation, liver disease, and above all, in renal dysfunction. Retention of amyloidogenic protein has been attributed to several factors including type of dialysis membrane, prolonged uremic state and/or decreased diuresis, advanced glycation end products, elevated levels of cytokines and dialysate. Dialysis treatment per se has been considered to be an inflammatory stimulus, inducing cytokine production (such as interleukin-1, tumor necrosis factor-α, interleukin-6) and complement activation. The released cytokines are thought to stimulate the synthesis and release of β2M by the macrophages and/or augment the expression of human leukocyte antigens (class I), increasing β2M expression. Residual renal function is probably the best determinant of β2M levels. Therefore, it has to be maintained as long as possible. In this article, we will focus our attention on the etiology of dialysis-related amyloidosis, its prevention, therapy, and future solutions.

Revisiting the Middle Molecule Hypothesis of Uremic Toxicity: A Systematic Review of Beta 2 Microglobulin Population Kinetics and Large Scale Modeling of Hemodialysis Trials In Silico

Background

Beta-2 Microglobulin (β2M) is a prototypical “middle molecule” uremic toxin that has been associated with a higher risk of death in hemodialysis patients. A quantitative description of the relative importance of factors determining β2M concentrations among patients with impaired kidney function is currently lacking.

Methods

Herein we undertook a systematic review of existing studies reporting patient level data concerning generation, elimination and distribution of β₂M in order to develop a population model of β₂M kinetics. We used this model and previously determined relationships between predialysis β₂M concentration and survival, to simulate the population distribution of predialysis β₂M and the associated relative risk (RR) of death in patients receiving conventional thrice-weekly hemodialysis with low flux (LF) and high flux (HF) dialyzers, short (SD) and long daily (LD) HF hemodialysis sessions and on-line hemodiafiltration at different levels of residual renal function (RRF).

Results

We identified 9 studies of 106 individuals and 156 evaluations of or more compartmental kinetic parameters of β₂M. These studies used a variety of experimental methods to determine β₂M kinetics ranging from isotopic dilution to profiling of intra/inter dialytic concentration changes. Most of the patients (74/106) were on dialysis with minimal RRF, thus facilitating the estimation of non-renal elimination kinetics of β₂M. In large scale (N = 10000) simulations of individuals drawn from the population of β₂M kinetic parameters, we found that, higher dialytic removal materially affects β₂M exposures only when RRF (renal clearance of β₂M) was below 2 ml/min. In patients initiating conventional HF hemodialysis, total loss of RRF was predicted to be associated with a RR of death of more than 20%. Hemodiafiltration and daily dialysis may decrease the high risk of death of anuric patients by 10% relative to conventional, thrice weekly HF dialysis. Only daily long sessions of hemodialysis consistently reduced mortality risk between 7–19% across the range of β₂M generation rate.

Conclusions

Preservation of RRF should be considered one of the therapeutic goals of hemodialysis practice. Randomized controlled trials of novel dialysis modalities may require large sample sizes to detect an effect on clinical outcomes even if they enroll anuric patients. The developed population model for β₂M may allow personalization of hemodialysis prescription and/or facilitate the design of such studies by identifying patients with higher β₂M generation rate.

The myriad of diseases that present with polyostotic bone lesions

Many diseases result in polyostotic bone lesions including benign entities, benign entities with malignant potential, intermediate entities, and malignant entities. Imaging plays a key role in identifying complications of these disorders, most importantly malignant transformation of a benign lesion. The most common polyostotic bone lesions are reviewed and examples of malignant transformation are highlighted.

Imaging Findings and Evaluation of Metabolic Bone Disease

Bone is a dynamic organ of the endoskeleton, playing an important role in structural integrity, mineral reservoirs, blood production, coagulation, and immunity. Metabolic bone disease encompasses a broad spectrum of inherited and acquired disorders that disrupt the normal homeostasis of bone formation and resorption. For patients affected by these processes, radiologic imaging plays a central role in diagnosis, monitoring treatment, and risk stratification. Radiologists should be familiar with the diseases, intimately aware of the imaging findings, and possessive of multimodality expertise to wisely guide the best practice of medicine. The purpose of this paper is to review the imaging features and characteristics of the most common types of metabolic bone disease with highlights of clinically relevant information so that readers can better generate appropriate differential diagnoses and recommendations. For this review, a thorough literature search for the most up-to-date information was performed on several key types of metabolic bone disease: osteoporosis, osteomalacia, rickets, scurvy, renal osteodystrophy, hyperparathyroidism, Paget’s disease, osteogenesis imperfecta, acromegaly, and osteopetrosis. Although they all affect the bone, these diseases have both shared characteristic features that can be discerned through imaging.

Radiologic case study. Dialysis-related amyloidosis

A 59-year-old woman presented with worsening bilateral hip pain for 6 months. She had been receiving hemodialysis for 12 years.

Various musculoskeletal manifestations of chronic renal insufficiency

Musculoskeletal manifestations in chronic renal insufficiency are caused by complex bone metabolism alterations, now described under the umbrella term of chronic kidney disease mineral- and bone-related disorder (CKD-MBD), as well as iatrogenic processes related to renal replacement treatment. Radiological imaging remains the mainstay of disease assessment. This review aims to illustrate the radiological features of CKD-MBD, such as secondary hyperparathyroidism, osteomalacia, adynamic bone disease, soft-tissue calcifications; as well as features associated with renal replacement therapy, such as aluminium toxicity, secondary amyloidosis, destructive spondyloarthropathy, haemodialysis-related erosive arthropathy, tendon rupture, osteonecrosis, and infection.

Remitting seronegative symmetrical synovitis with pitting edema syndrome in a chronic hemodialysis patient

A 75-year-old male who was undergoing chronic hemodialysis developed abrupt-onset pitting edema and pain in the dorsum of both hands and feet. Biochemical analysis disclosed increased C-reactive protein, and negative rheumatoid factor and antinuclear antibody. Radiological examination showed no bony erosion. Computed tomography and gallium scintigraphy revealed no active infection or neoplasms. The clinical diagnosis was remitting seronegative symmetrical synovitis with pitting edema (RS₃PE) syndrome. The pitting edema and inflammatory response quickly subsided after low-dose prednisolone therapy. This case demonstrates that RS₃PE syndrome could be a differential diagnosis in elderly patients undergoing dialysis who develop pitting edema and joint pain.

β(2)-microglobulin amyloidosis

Dialysis-related amyloidosis (DRA) is a clinical syndrome of pain, loss of function and other symptoms due to the deposition of amyloid consisting of β(2)-microglobulin (β(2)m) in the musculoskeletal system. The condition is seen in patients who suffer from chronic kidney disease and are treated with hemodialysis for a long time. Even though β(2)m easily can be manipulated to form amyloid in laboratory experiments under non-physiological conditions the precise mechanisms involved in the formation of β(2)m-amyloid in patients with DRA have been difficult to unravel. The current knowledge which is reviewed here indicates that conformational fluctuations centered around the D-strand, the DE-loop, and around the cis-configured Pro32 peptide bond are involved in β(2)m amyloidosis. Also required are highly increased concentrations of circulating β(2)m and possibly various post-translational modifications mediated by the pro-inflammatory environment in uremic blood, together with the influence of divalent metal ions (specifically Cu(2 +)), uremic toxins, and dialysis-enhanced redox-processes. It seems plausible that domain-swapped β(2)m dimers act as building blocks of β-spine cross-β -sheet fibrils consisting of otherwise globular, roughly natively folded protein. An activated complement system and cellular activation perpetuate these reactions which due to the affinity of β(2)m-amyloid for the collagen of synovial surfaces result in the DRA syndrome.

Fine-needle aspiration diagnosis of an intraosseous amyloidoma

Fine-needle aspiration (FNA) is frequently used as the initial diagnostic procedure for the investigation of bone and soft tissue masses. The majority of the lesions detected will represent metastatic carcinoma. Amyloid is a rare cause of a bone mass, with less than 15 published reports describing amyloid deposition within bone. The majority of reported cases involve the vertebral column. We report the finding of a massive amyloidoma of the iliac wing in a 46-year-old man. FNA smears and cell block preparations demonstrated fragments of waxy acellular material misinterpreted as necrotic debris. Subsequent open biopsy established the diagnosis of amyloid with congo red staining demonstrating apple green birefringence. Subsequent workup disclosed the patient to have anemia, hypogammaglobulinemia and trace monoclonal light chain gammopathy. Bone marrow examination revealed CD138a positive lambda restricted plasma cells consistent with plasma cell dyscrasia. Careful attention to the staining characteristics of amyloid in FNA derived material should allow the diagnosis of amyloidoma.

Sonographic subclinical entheseal involvement in dialysis patients

Long-term dialysis treatment can be associated with several musculoskeletal complications. Entheseal involvement in dialysis patients remains rarely studied as its prevalence is underestimated due to its often asymptomatic presentation. The aims of the study were to determine the prevalence of subclinical enthesopathy in haemodialysis and peritoneal dialysis patients at the lower limb level, to investigate the inter-observer reliability of ultrasound assessment and to analyse the influence of biometric and biochemical parameters. Ultrasound examination was conducted at the entheses of the lower limbs level in 33 asymptomatic dialysis patients and 33 healthy adopting the Glasgow Ultrasound Enthesitis Scoring System (GUESS). The inter-observer reliability was calculated in 15 dialysis patients. Ultrasound found at least one sign of enthesopathy in 165 out of 330 (50%) entheses of dialysis patients. In healthy subjects, signs of enthesopathy were present in 54 out of 330 (16.3%) entheses (p < 0.0001). No power Doppler signal was detected in healthy controls, in contrast to four of 330 entheses of dialysis patients. No US signs of soft tissue amyloid deposits were found. The GUESS score was significantly higher in dialysis patients than in controls (p < 0.0001). There was no difference in terms of enthesopathy between haemodialysis and peritoneal dialysis. Dialysis duration resulted to be the most important predictor for enthesopathy (p = 0.0004), followed by patient age (p = 0.02) and body mass index (p = 0.035). Parathormone, calcium, phosphorus, C-reactive protein, cholesterol and triglycerides apparently did not play a relevant role in favour of enthesopathy. The inter-observer reliability showed an excellent agreement between sonographers with different degree of experience. Our results demonstrated a higher prevalence of subclinical enthesopathy in both haemodialysis and peritoneal dialysis patients than in healthy subjects. Follow-up will provide further information with respect to the predictive value of US findings for the development of symptomatic dialysis-related arthropathy.

Mouse model to study human A beta2M amyloidosis: generation of a transgenic mouse with excessive expression of human beta2-microglobulin

Patients on long-term hemodialysis can develop dialysis-related amyloidosis (DRA) due to deposition of beta(2)-microglobulin (beta(2)m) into amyloid fibrils (Abeta(2)M). Despite intensive biochemical studies, the pathogenesis of amyloid deposition in DRA patients remains poorly understood. To elucidate the mechanisms that underlie Abeta(2)M fibril formation in DRA, we generated transgenic mice that overexpress human beta(2)m protein in a mouse beta(2)m gene knockout background (hB2MTg(+/+) mB2m(+/+)). The hB2MTg(+/+)mB2m(-/-) mice express a high level of human beta(2)m protein in many tissues as well as a high plasma beta(2)m concentration (192.8 mg/L). This concentration is >100 times higher than that observed in healthy humans and >4 times higher than that detected in patients on dialysis. We examined spontaneous and amyloid fibril-induced amyloid deposition in these mice. Amyloid deposition of beta(2)m protein was not observed in aged or amyloid fibril injected animals. However, mouse senile apolipoprotein A-II amyloidosis (AApoAII) was detected, particularly in the joints of mice that were injected with AApoAII amyloid fibrils. This study demonstrates that this mouse model could be valuable in studying the components and conditions that promote DRA, and indicates that high plasma concentrations of hbeta(2)m as well as seeding with pre-existing amyloid fibrils may not be sufficient to induce Abeta(2)M.

Current concepts in the evaluation of multiple myeloma with MR imaging and FDG PET/CT

Multiple myeloma is a heterogeneous group of plasma cell neoplasms that primarily involve bone marrow but also may occur in the soft tissue. Although the disease varies in its manifestations and its course, it is eventually fatal in all cases. Over the past 2 decades, significant advances have been made in our understanding of the genetics and pathogenesis of multiple myeloma and in its treatment. The use of magnetic resonance (MR) imaging and fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) has improved sensitivity for the detection of this disease. PET aids in the identification of active multiple myeloma on the basis of FDG uptake, and MR imaging helps identify multiple myeloma from its infiltration of normal fat within the bone marrow, which occurs in characteristic patterns that correlate with the disease stage. The increased sensitivity of these advanced cross-sectional imaging techniques has led to further refinement of the classic Durie and Salmon staging system. In addition, these imaging techniques allow a more reliable assessment of the disease response to treatment with current regimens, which may include autologous stem cell transplantation as well as various medications. In lesions that respond to chemotherapeutic agents, the replacement of previously infiltrated marrow by fat is seen at MR imaging and decreased FDG uptake is seen at FDG PET; however, a lengthy and intensive regimen may be necessary before the MR imaging appearance of marrow normalizes. Lytic lesions seen at CT almost always persist even after successful treatment. To provide an accurate assessment, radiologists must be familiar not only with the appearances of multiple myeloma and its mimics but also with common treatment-related findings.

Miscellaneous conditions of the shoulder: anatomical, clinical, and pictorial review emphasizing potential pitfalls in imaging diagnosis

The purpose of this article is to review the key imaging findings in major categories of pathology affecting the shoulder joint including hydroxyapatite deposition disease, rotator cuff interval pathology, acromioclavicular joint pathology, glenohumeral osteoarthrosis, and synovial inflammatory processes, with specific emphasis on findings that have associated pitfalls in imaging diagnosis. The pathophysiology and clinical manifestations of the above mentioned categories of pathology will be reviewed, followed in each section by a detailed pictorial review of the key imaging findings in each category including plain film, computed tomography, and magnetic resonance imaging findings as applicable. Imaging challenges that relate to both diagnosis and characterization will be addressed with each type of pathology. The goal is that after reading this article, the reader will be able to recognize the key imaging findings in major categories of pathology affecting the shoulder joint and will become familiar with the potential pitfalls in their imaging diagnosis.

Sonographic evaluation of entheseal sites of the lower extremity in patients undergoing hemodialysis

PURPOSE

To evaluate the entheseal sites of the lower extremities in patients on hemodialysis using the Glasgow Ultrasound Enthesitis Scoring System (GUESS) and to correlate the findings with the duration of hemodialysis and patient scores.

METHODS

Forty-nine patients who were on hemodialysis for at least 2 years were grouped according to duration of hemodialysis. Total GUESS scores; total enthesophyte, erosion, and bursitis scores; and tendon thicknesses were calculated, compared between groups, and correlated with duration of dialysis.

RESULTS

There was a statistically significant correlation between duration of hemodialysis and total GUESS score (p < 0.001, r = 0.81) and also between the total enthesophyte and erosion scores (p < 0.001). If severe enthesitis was defined as a total GUESS score of more than 18, receiver operating characteristic (ROC) curve analysis revealed that a cutoff point of 10 years for the duration of hemodialysis would predict severe enthesal damage with 83% sensitivity and 93% specificity (area under the ROC curve, 0.92; 95% confidence interval, 0.83-1.00).

CONCLUSION

Hemodialysis results in entheseal site changes that worsen with extended duration of hemodialysis, especially after 10 years.