Atypical posterior reversible encephalopathy syndrome in a noncompliant hemodialysis patient: Case report and literature review

Posterior reversible encephalopathy syndrome (PRES) is a reversible vasogenic brain edema in patients who present with seizure, headache, visual disturbance, and altered mental status, and a characteristic neuroimaging profile. Although PRES predominantly affects the bilateral parieto‐occipital areas, involvement of the frontal and temporal lobes, basal ganglia, brainstem, and cerebellum is not uncommon. Isolated involvement of the brainstem and cerebellum sparing the parieto‐occipital lobe is rarely reported. Here, we describe a 47‐year‐old man with end‐stage renal disease on chronic hemodialysis who presented with prominent hypertension and coma after missing three dialysis sessions. On examination, there was paucity of focal neurologic signs. Diagnosis of PRES was based on brain magnetic resonance imaging findings that were consistent with vasogenic edema of the pons and cerebellum without involvement of other areas. With antihypertensive therapy and intense ultrafiltration during hemodialysis, the patient's blood pressure and consciousness returned to normal, along with complete resolution of the abnormal imaging findings. This case stresses that noncompliance with dialysis should be considered a risk factor for PRES. This case is considered relative to the available literature on three patients with brainstem variant of PRES.     

Dialysis disequilibrium syndrome presenting as a focal neurological deficit

We report a patient suffering from chronic kidney disease who presented to us with severe pulmonary edema. His clinical, laboratory, and sonological parameters were suggestive of end-stage renal disease. Hemodialysis was initiated, and after 48 hours (3 sessions of hemodialysis) he became drowsy and a neurological examination revealed left upper limb monoplegia with left facial palsy. Urgent computerized tomography scan of the brain revealed diffuse hypodensity in the cerebral white matter bilaterally, and brain magnetic resonance imaging showed diffuse hyperintensity in the cerebral white matter bilaterally, right internal capsule and external capsule on fluid attenuated inversion recovery and T2 sequences (hypointense on T1 sequence). He made a gradual but complete neurological recovery and was discharged 2 weeks later with normal neurological status. A repeat brain magnetic resonance imaging on follow-up 6 weeks later revealed complete resolution of the white matter abnormalities.     

Renal dysplasia masquerading as a renal mass in a child on hemodialysis

Pathological renal mass is uncommon in children. It is important to differentiate this from a benign mass or mass‐like lesion (pseudomass) for proper management. Renal dysplasia is a common finding in patients with end stage renal disease and can mimic a renal mass. Here, we report a 16‐year‐old girl on hemodialysis who was found to have a nodular right renal mass in the sonogram. Magnetic resonance imaging confirmed the nodular mass. She underwent right nephrectomy and the histopathology revealed features of renal dysplasia and end stage kidney disease without any evidence of malignancy. No further treatments were necessary. This case demonstrates that a nodular renal mass in dialysis patients does not always mean malignancy and could be a pseudomass from severe renal dysplasia. Since a sonogram may not be able to clearly define the etiology of solid mass in these patients, further evaluations including a renal histology and/or other imaging modalities are often necessary.     

Acute kidney injury in a postpartum woman with paroxysmal nocturnal hemoglobinuria: A case report and literature review

Paroxysmal nocturnal hemoglobinuria is a rare clonal hematopoietic stem cell disorder characterized by intravascular hemolysis, hemoglobinuria, and inflammatory thrombotic state. Intravascular hemolysis in paroxysmal nocturnal hemoglobinuria (PNH) can lead to acute and chronic renal injury through hemoglobin‐mediated toxicity. A 32‐year‐old pregnant woman with myelodysplastic syndrome was admitted to our hospital with severe preeclampsia. Shortly after an urgent caesarean section, she became obtunded and showed signs of acute kidney injury (AKI) with anuria, severe intravascular hemolysis, and hypermagnesemia. She was diagnosed with PNH with a positive Ham test and flow cytometry analysis. Renal magnetic resonance imaging revealed decreased signal intensity in the renal cortex due to hemosiderin deposition. Hemodialysis, plasma exchange, and administration of corticosteroids ameliorated her clinical condition and renal function. This case illustrates that careful management is required to prevent postpartum AKI in pregnant women with PNH.     

Imaging manifestations of sepsis‐associated encephalopathy

The purpose of this study was to retrospectively analyze the clinical and imaging data of sepsis‐associated encephalopathy (SAE) following infantile diarrhea. Eight infants were diagnosed with SAE after diarrhea and assessed using computed tomography (CT) and magnetic resonance imaging (MRI). The main symptoms present in each of the eight patients were fever, diarrhea, seizures, and changes in consciousness. From cranial CT examination, five patients showed normal results, two displayed cerebral edema, and one displayed slightly lower density areas in the frontal and parietal lobes. There were four patients examined through MRI: one patient displayed slightly widened cerebral sulci; two displayed edema in the white cerebral matter and basal ganglia with gyriform enhancement after contrast; one displayed an abnormal bilateral signal in the occipital lobes and another in the frontoparietal lobe; and one displayed a diffuse abnormal signal in the white matter of both cerebral hemispheres and basal ganglia. Imaging manifestations of SAE included encephaledema or abnormal signals in the white matter and basal ganglia. CT examination can exclude other cerebral pathologies causing brain dysfunction in early stages. MRI examination can provide more information to aid in the early diagnosis of SAE.     

Primary brachial vein transposition for hemodialysis access: Report of a case and review of the literature

The superiority of autogenous fistulae in patients with end‐stage renal disease, performing hemodialysis, is well established and largely accepted. However, in case that superficial veins in the upper arm are not available for fistula construction, brachial vein transposition may be a viable alternative prior to graft placement. This transposition could be done as a primary or staged procedure, depending on the vein size. We present the case of a 63‐year‐old male patient with a thrombosed arteriovenous graft in the forearm and a large brachial vein in the ipsilateral upper arm. A one‐stage (primary) brachial vein transposition was performed. The fistula, 10 months after its construction, is still patent. No complications have occurred.     

Heparin‐induced thrombocytopenia due to heparin lock in a hemodialysis patient: A case report

Heparin‐induced thrombocytopenia (HIT) is a potentially fatal clinical condition which can develop after exposure to unfractionated or low‐molecular‐weight heparins. Even small doses of heparin such as heparin flushes in hemodialysis catheter can induce the development of HIT. However, the true incidence of heparin lock‐related HIT is unknown. We report a 58‐year‐old woman with acute kidney injury because of obstructive uropathy who developed HIT after heparin‐free hemodialysis. She was found to have severe thrombocytopenia with deep vein thrombosis of left lower limb and arterial thrombosis of the right anterior and middle cerebral arteries. The heparin‐platelet factor 4 antibody was positive and she was put on plasmapharesis. However, her condition further deteriorated and succumbed shortly. Heparin lock solution in the hemodialysis catheter was believed to be the cause of HIT in our patient.     

Spontaneous calf hematoma in a patient with diabetic nephropathy receiving maintenance hemodialysis: A case report and review of the literature

We report the outcome of a 52‐year‐old patient with diabetic nephropathy and receiving maintenance hemodialysis (HD) using low molecular weight heparin (LMWH) as an anticoagulant for 2 years. He presented right lower limb pain accompanied with difficulty in walking for 2 months, and had no history of bleeding tendency or trauma. Physical examination revealed marked swelling and tenderness on his right lower limb. By ultrasound and magnetic resonance imaging (MRI) diagnoses, the calf hematoma was diagnosed and identified with venous thrombosis. Following treatment with heparin‐free HD, the swelling regressed and pain subsided, and a follow‐up MRI showed complete dissolution of hematoma. However, similar symptoms recurred in the right upper limb after 2 months without any predisposition, he was just placed on HD with LMWH, and symptoms regressed following the aforementioned therapy. This suggests that HD patients, especially with diabetic nephropathy having extremity hematoma, should be watched for the development of spontaneous hemorrhage that can be differentially diagnosed by imaging tests, such as MRI, and can be effectively treated with heparin‐free HD.     

Kienböck's disease associated with radiocephalic fistula formation in a patient with end‐stage renal disease

Kienböck's disease, which consists of osteonecrosis and collapse of the lunate bone, causes chronic pain and dysfunction of the wrist. Patients on hemodialysis are occasionally present with wrist pain, but Kienböck's disease is rarely reported in dialysis patients. This case study describes Kienböck's disease in a patient with end‐stage renal disease on hemodialysis. A 39‐year‐old male with a 1‐year history of hemodialysis presented with left wrist pain that increased progressively over 6 months. The patient had no history of trauma or any other risk factors known to be associated with Kienböck's disease. Physical examination of the wrist at the site of the arteriovenous fistula showed swelling and tenderness with decreased range of motion. Radiographic examination showed articular collapse and fracture of the body of lunate consistent with stage IIIb Kienböck's disease. An intercarpal arthrodesis with autogenous bone graft was performed.     

Comparing frozen saphenous vein with Gore-tex in vascular access for chronic hemodialysis

Performing chronic hemodialysis in patients suffering from end‐stage renal disease needs a suitable vascular access like arteriovenous fistula in the upper limbs and bridge fistula in the upper or lower limbs, and also use of permanent and temporary catheters. The purpose of this study is to compare frozen saphenous vein versus using synthetic Gore‐tex vascular graft for A–V fistula. In the prospective randomized study, 70 patients needing for dialysis access were randomly divided into two groups. We performed the frozen saphenous vein A–V fistula in the test group and the Gore‐tex fistula in the control group. An assessment included function criteria (fistula thrill and murmur) and complications (infection and thrombosis) in planned intervals. At the end of the follow‐up period, the flow rates of all fistulas were assessed by Doppler sonography. The data were compared. Comparing the function criteria (fistula murmur and thrill) and the flow rate of the test group (frozen saphenous A–V fistula) and the control group (Gore‐tex method) showed no significant difference and also no significant difference between two groups in thrombosis. Infection rate of the Gore‐tex method was significantly high (p < 0.05). Arteriovenous fistula was an acceptable alternative in chronic hemodialysis, and frozen saphenous vein arteriovenous fistula was superior to Gore‐tex arteriovenous graft in some aspects.     

Esophageal actinomycosis in a patient with end‐stage renal disease

Actinomycosis of esophagus is uncommon. Herpes simplex virus, cytomegalovirus, candidiasis, tuberculosis, and other fungal infections are the commonly reported infections in both immunocompromised and immunocompetent patients. We report a case of esophageal actinomycosis in an end‐stage renal disease patient. A 28‐year‐old lady, known case of systemic lupus erythematosus, hepatitis B virus infection with end‐stage renal disease on regular maintenance hemodialysis since 5 years presented with history of epigastric pain and odynophagia for 1 week. Her upper gastrointestinal endoscopic examination revealed extensive necrotic areas with membrane in the esophagus. Histopathology revealed actinomycotic colonies and bacterial clumps. She was treated with intravenous penicillin followed by oral ampicillin for 6 months. She showed marked clinical improvement, and repeat endoscopy showed healing of ulceration and no evidence of actinomycosis.     

Alzheimer disease classification using KPCA,LDA, and multi‐kernel learning SVM

Early diagnosis of Alzheimer disease (AD) and mild cognitive impairment (MCI) is always useful. Preventive measures might have an impact on reducing AD risk factors. Structural magnetic resonance (MR) imaging, one of the vital sensitive biomarkers for cerebral atrophy in the brain, is used to extract volumetric feature by FreeSurfer and the CIVET toolbox. All of the structural magnetic resonance imaging (s‐MRI) data that we used were downloaded from the Alzheimer's disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu) of imaging data. This novel approach is applied for the diagnosis of AD and MCI from healthy controls (HCs) combining extracted features with the MMSE (mini‐mental state examination) scores, applying a two sample t‐test to select a subset of features. The subset of features is fed to kernel principal component analysis (KPCA) module to project data onto the reduced principal component coefficients at higher dimensional kernel space to increase the linear separability. Then, the kernel PCA coefficients are projected into the more efficient linear discriminant space using linear discriminant analysis. A multi‐kernel learning support vector machine (SVM) is used on newly projected data for stratification of AD and MCI from HCs. Using this approach, we obtain 93.85% classification accuracy when detecting AD from HCs for segmented volumetric features (using FreeSurfer) with high sensitivity and specificity. When distinguishing MCI from HCs and AD using volumetric features after subcortical segmentation, the detection rate reaches 86.54% and 75.12%, respectively.     

Heparin‐induced thrombocytopenia in a hemodialysis patient treated with fondaparinux: Nephrologists between two fires

Heparin‐induced thrombocytopenia (HIT) is caused by heparin exposure and presents with reduced platelet count. Patients undergoing hemodialysis (HD) treatment have increased risk of developing HIT due to prolonged exposure to unfractionated heparin or low‐molecular weight heparin. We report a 79‐year‐old male patient with end‐stage renal disease who developed type‐II HIT during maintenance HD. Platelet count of the patient decreased gradually and antiplatelet factor IV antibody was found to be positive. The patient was treated with fondaparinux and continued heparin‐free HD. Unfortunately, despite favorable initial response without any thrombotic episodes, the patient died due to severe sepsis complicated by gastrointestinal hemorrhage.     

Control of the in vivo Biodistribution of Hybrid Nanoparticles with Different Poly(ethylene glycol) Coatings

Fluorescent nanoparticles containing a gadolinium oxide core are very attractive because they are able to combine both imaging (fluorescence imaging, magnetic resonance imaging) and therapy (X‐ray therapy and neutron‐capture therapy) techniques. The exploitation of these multifunctional particles for in vivo applications requires accurate control of their biodistribution. The postfunctionalization of these particles by four different poly(ethylene glycol) derivatives, which differ by chain length and end group, exerts a great influence on the ζ potential of the nanoparticles and on their biodistribution after intravenous injection to HEK‐β3‐tumor‐bearing mice. This study reveals that the behavior of PEGylated nanoparticles, which was monitored by in vivo fluorescence imaging, depends on both the chain length and the end group of the PEG chain.     

Guiding Brain‐Tumor Surgery via Blood–Brain‐Barrier‐Permeable Gold Nanoprobes with Acid‐Triggered MRI/SERRS Signals

Surgical resection is a mainstay in the treatment of malignant brain tumors. Surgeons, however, face great challenges in distinguishing tumor margins due to their infiltrated nature. Here, a pair of gold nanoprobes that enter a brain tumor by crossing the blood–brain barrier is developed. The acidic tumor environment triggers their assembly with the concomitant activation of both magnetic resonance (MR) and surface‐enhanced resonance Raman spectroscopy (SERRS) signals. While the bulky aggregates continuously trap into the tumor interstitium, the intact nanoprobes in normal brain tissue can be transported back into the blood stream in a timely manner. Experimental results show that physiological acidity triggers nanoparticle assembly by forming 3D spherical nanoclusters with remarkable MR and SERRS signal enhancements. The nanoprobes not only preoperatively define orthotopic glioblastoma xenografts by magnetic resonance imaging (MRI) with high sensitivity and durability in vivo, but also intraoperatively guide tumor excision with the assistance of a handheld Raman scanner. Microscopy studies verify the precisely demarcated tumor margin marked by the assembled nanoprobes. Taking advantage of the nanoprobes' rapid excretion rate and the extracellular acidification as a hallmark of solid tumors, these nanoprobes are promising in improving brain‐tumor surgical outcome with high specificity, safety, and universality.     

Timely Visualization of the Collaterals Formed during Acute Ischemic Stroke with Fe3O4 Nanoparticle‐based MR Imaging Probe

Ischemic stroke is one of the major leading causes for long‐term disability and mortality. Collateral vessels provide an alternative pathway to protect the brain against ischemic injury after arterial occlusion. Aiming at visualizing the collaterals occurring during acute ischemic stroke, an integrin α_vβ₃‐specific Fe₃O₄–Arg‐Gly‐Asp (RGD) nanoprobe is prepared for magnetic resonance imaging (MRI) of the collaterals. Rat models are constructed by occluding the middle cerebral artery for imaging studies of cerebral ischemia and ischemia–reperfusion on 7.0 Tesla MRI using susceptibility‐weighted imaging sequence. To show the binding specificity to the collaterals, the imaging results acquired with the Fe₃O₄–RGD nanoprobe and the Fe₃O₄ mother nanoparticles, respectively, are carefully compared. In addition, an RGD blocking experiment is also carried out to support the excellent binding specificity of the Fe₃O₄–RGD nanoprobe. Following the above experiments, cerebral ischemia–reperfusion studies show the collateral dynamics upon reperfusion, which is very important for the prognosis of various revascularization therapies in the clinic. The current study has, for the first time, enabled the direct observation of collaterals in a quasi‐real time fashion and further disclosed that the antegrade flow upon reperfusion dominates the blood supply of primary ischemic tissue during the early stage of infarction, which is significantly meaningful for clinical treatment of stroke.     

Sequential molecularly targeted drug therapy including axitinib for a patient with end‐stage renal failure and metastatic renal cell carcinoma

A 62‐year‐old male patient with end‐stage renal disease and metastatic renal cell carcinoma (RCC) was referred to our hospital. Sequential targeted therapy consisting of sorafenib, sunitinib, and everolimus was administered, but the patient's disease gradually progressed. Axitinib was subsequently administered at a decreased dose of 6 mg/day for 2 weeks, after which the dose was escalated to 10 mg/day. Axitinib therapy was maintained for a total of 6 months without severe adverse effects. Sequential molecularly targeted drug therapy including axitinib, with careful monitoring, is one possible treatment option for patients with metastatic RCC with renal impairment.     

A multi‐modal,multi‐atlas‐based approach for Alzheimer detection via machine learning

The use of biomarkers for early detection of Alzheimer's disease (AD) improves the accuracy of imaging‐based prediction of AD and its prodromal stage that is mild cognitive impairment (MCI). Brain parcellation‐based computer‐aided methods for detecting AD and MCI segregate the brain in different anatomical regions and use their features to predict AD and MCI. Brain parcellation generally is carried out based on existing anatomical atlas templates, which vary in the boundaries and number of anatomical regions. This works considers dividing the brain based on different atlases and combining the features extracted from these anatomical parcellations for a more holistic and robust representation. We collected data from the ADNI database and divided brains based on two well‐known atlases: LONI Probabilistic Brain Atlas (LPBA40) and Automated Anatomical Labeling (AAL). We used baselines images of structural magnetic resonance imaging (MRI) and ¹⁸F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) to calculate average gray‐matter density and average relative cerebral metabolic rate for glucose in each region. Later, we classified AD, MCI and cognitively normal (CN) subjects using the individual features extracted from each atlas template and the combined features of both atlases. We reduced the dimensionality of individual and combined features using principal component analysis, and used support vector machines for classification. We also ranked features mostly involved in classification to determine the importance of brain regions for accurately classifying the subjects. Results demonstrated that features calculated from multiple atlases lead to improved performance compared to those extracted from one atlas only.     

Image‐guided navigation of single‐element focused ultrasound transducer

The spatial specificity and controllability of focused ultrasound (FUS), in addition to its ability to modify the excitability of neural tissue, allows for the selective and reversible neuromodulation of the brain function, with great potential in neurotherapeutics. Intraoperative magnetic resonance imaging (MRI) guidance has limitations due to its complicated examination logistics, such as fixation through skull screws to mount the stereotactic frame, simultaneous sonication in the MRI environment, and restrictions in choosing MR‐compatible materials. To overcome these limitations, an image‐guidance system based on optical tracking and preoperative imaging data is developed, separating the imaging acquisition for guidance and sonication procedure for treatment. Techniques to define the local coordinates of the focal point of sonication are presented. First, mechanical calibration detects the concentric rotational motion of a rigid‐body optical tracker, attached to a straight rod mimicking the sonication path, pivoted at the virtual FUS focus. The spatial error presented in the mechanical calibration was compensated further by MRI‐based calibration, which estimates the spatial offset between the navigated focal point and the ground‐truth location of the sonication focus obtained from a temperature‐sensitive MR sequence. MRI‐based calibration offered a significant decrease in spatial errors (1.9 ± 0.8 mm; 57% reduction) compared to the mechanical calibration method alone (4.4 ± 0.9 mm). Using the presented method, pulse‐mode FUS was applied to the motor area of the rat brain, and successfully stimulated the motor cortex. The presented techniques can be readily adapted for the transcranial application of FUS to intact human brain. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 177–184, 2012