Role of Vascular Access as a Risk Factor for Infections in Hemodialysis

Infections are a major cause of morbidity and mortality in chronic hemodialysis patients. This single center prospective study was carried out to determine the incidence and risk factors for infection in hemodialysis patients and plan appropriate strategies to reduce the risk of infection. A total of 84 consecutive patients who were initiated on hemodialysis over a 2-year period were followed until they either received a kidney transplant or died. In our hospital, as a policy, patients are offered hemodialysis as a bridge therapy to a kidney transplant. The mean duration of follow up was 3 months (range 1-11.8 months). The factors associated with at least one episode of infection were evaluated. Statistical analysis was done by multivariate stepwise logistic regression method. Fifty-one patients had a total of 57 episodes (67.8%) of infection. Of the 44 episodes of acute bacterial infections, vascular access exit site infection was the commonest followed by septicemia (13 patients, 29.5%). Staphylococcus aureus was the commonest bacterial isolate observed in 14 patients. On multivariate analysis, three risk factors for infection were identified: (1) nonarteriovenous fistula (AVF) vascular access for hemodialysis (p = 0.02), (2) increased number of hemodialysis sessions (p = 0.03), and (3) lower serum calcium level (p = 0.02). NonAVF vascular access was found to be the most important risk factor for infection in hemodialysis patients. Creation of an AV fistula, preferably at an early stage, appears beneficial for minimizing the risk of infection even in patients who are on short-term hemodialysis as a bridge therapy towards a kidney transplant.

Intra-operative 3-T MRI for paediatric brain tumours: challenges and perspectives

MRI is the ideal modality for imaging intracranial tumours. Intraoperative MRI (ioMRI) makes it possible to obtain scans during a neurosurgical operation that can aid complete macroscopic tumour resection—a major prognostic factor in the majority of brain tumours in children. Intraoperative MRI can also help limit damage to normal brain tissue. It therefore has the potential to improve the survival of children with brain tumours and to minimise morbidity, including neurological deficits. The use of ioMRI is also likely to reduce the need for second look surgery, and may reduce the need for chemotherapy and radiotherapy. Highfield MRI systems provide better anatomical information and also enable effective utilisation of advanced MRI techniques such as perfusion imaging, diffusion tensor imaging, and magnetic resonance spectroscopy. However, high-field ioMRI facilities require substantial capital investment, and careful planning is required for optimal benefit. Safe ioMRI requires meticulous attention to detail and rigorous application of magnetic field safety precautions. Interpretation of ioMRI can be challenging and requires experience and understanding of artefacts that are common in the intra-operative setting.

Inferior epigastric artery pseudoaneurysms

INTRODUCTION

Inferior epigastric artery (IEA) pseudoaneurysms are recognised complications of abdominal wall procedures, and a variety of approaches including surgical excision and ligation, percutaneous procedures and conservative management have been employed in treating this rare complication.

METHODS

We describe a case of an IEA pseudoaneurysm diagnosed on computed tomography (CT) angiography, 14 days following a laparoscopic assisted low anterior resection, which was managed successfully with surgical excision and ligation. A review of the literature identified 32 reports of this complication since 1973 with 69% of cases occurring since 2000.

FINDINGS

The main aetiology of IEA pseudoaneurysm was abdominal surgery (n=20); 65% of cases were attributable to abdominal wound closure or laparoscopic surgery. Two-thirds (66%) of patients presented between 11 and 63 days, and all except 1 case presented with discomfort, abdominal mass or haemodynamic instability. Colour Doppler ultrasonography was the imaging modality of choice (n=18), either alone or in combination with computed tomography and/or angiography. Surgical ligation and excision and percutaneous coil embolisation formed the mainstay of attempted treatments (69%), particularly following treatment failure using an alternative technique.

CONCLUSIONS

The incidence of iatrogenic IEA pseudoaneurysms appears to be increasing. Awareness of this rare complication is of clinical importance to avoid excessive morbidity for affected individuals.

Juxtaposed "kissing" stents as a technique to preserve both limbs of a bifurcating renal artery

Percutaneous revascularization with balloon expandable stent placement and/or balloon angioplasty has been proven to be an effective alternative for renal artery bypass surgery for management of renal artery stenosis. Endovascular stent deployment has been proven to be superior to balloon angioplasty alone, especially for ostial lesions in terms of maintaining long-term patency. Here we describe a case report for deployment of two Palmaz stents with simultaneous utilization of brachial and femoral routes. Technical aspects for this procedure, especially adaptation of coronary guide wire systems in management of renal artery stenosis were discussed.

Appendicitis in a Spigelian hernia: an unusual cause for a tender right iliac fossa mass

Spigelian hernias are a rare type of hernia through the Spigelian aponeurosis, whose contents commonly include omentum or small bowel. In the absence of incarceration or strangulation, they can be difficult to diagnose clinically. In the emergency setting, they can present rarely as a painful abdominal mass and computed tomography provides a reliable diagnostic imaging modality. We report an emergency presentation of a Spigelian hernia containing the appendix.

Endovascular covered stent repair of an intercostal artery patch dehiscence from a descending thoracic aortic aneurysm graft

PURPOSE

To describe the use of endovascular techniques to repair a descending thoracic aortic pseudoaneurysm at a site of patch dehiscence.

METHODS AND RESULTS

A 63-year-old hypertensive, diabetic female with a 4-cm aneurysm in the descending thoracic aorta underwent surgical repair with a 35-mm Dacron graft. Dehiscence of the intercostal arterial patch produced a large, 6-cm-diameter pseudoaneurysm that extended into the left thoracic cavity. An endovascular repair was planned using a Dacron stent-graft. Despite induced hypotension and an exteriorized, stiff exchange wire to enhance control of the delivery balloon catheter, the initial attempt failed to close the suture line defect. A customized polytetrafluoroethylene-covered, balloon-expandable stent was successfully deployed using the original stent-graft as a landmark. At 6 months, the contrast-enhanced spiral computed tomographic scan showed patency of the stent-graft and resorption of the pseudoaneurysm.

CONCLUSIONS

This communication describes the management of a surgical complication using balloon-expandable covered stents in contrast to either conventional surgery or self-expanding stent-grafts. Transesophageal ultrasound monitoring delineated the suture line leak, identified the position of the stent-grafts, and accurately demonstrated closure of the defect.

Acquired torticollis due to primary pyomyositis of the paraspinal muscles in an 11-year-old boy

Torticollis is characterised by tilting and rotation of the cervical spine in opposite directions. Causes can be congenital or acquired. Primary pyomyositis is a rare subacute deep bacterial infection of skeletal muscles that typically affects individuals under 20 years of age from tropical countries. Infrequently, pyomyositis occurs in individuals from temperate regions, usually in immunocompromised adults, and this is defined as secondary pyomyositis. We report a case of acquired torticollis due to primary pyomyositis of the paraspinal muscles in a previously healthy boy from the UK. A prolonged course of antibiotics and physiotherapy led to a complete resolution of his illness. We review how to differentiate pyomyositis from focal myositis, a more common inflammatory muscular cause of acquired torticollis.

Review of standard paediatric neuroradiology MRI protocols from 12 UK tertiary paediatric hospitals: is there much variation between centres?

AIM

To investigate how magnetic resonance imaging (MRI) examinations are protocolled in tertiary paediatric neuroradiology centres around the UK for some of the more common presentations encountered in paediatric neuroradiology, and to identify any variations of note.

MATERIALS AND METHODS

All 19 UK tertiary paediatric neuroradiology centres registered with the British Society of Neuroradiologists-Paediatric Group were contacted and asked if they could provide a copy of their standard MRI protocols. Twelve responded (63%) and 10 of the more common presentations were selected and the standard acquired sequences obtained at each participating centre were compared. Where available the collated protocols were also compared against current published guidance.

RESULTS

The basic sequences carried out by centres around the UK are similar; however, there are lots of variations overall. The only standardised protocol currently being implemented nationally in paediatric imaging is that for brain tumours. Otherwise, chosen protocols are generally dependent on the preferences and technical capabilities of individual centres. Suggested published protocols also exist for non-accidental injury (NAI), multiple sclerosis, epilepsy, and head and neck imaging.

CONCLUSIONS

The differences in MRI protocolling depend in part on technical capabilities and in part on the experience and preferences of the paediatric neuroradiologists at each centre. For most presentations, there is no consensus as to what constitutes the perfect protocol. The present results will be useful for specialist centres who may wish to review their current protocols, and for more generalist centres to use as a reference to guide their MRI protocolling.

OS03.5.A Corelation between longitudinal t2 MRI radiomic primary texture feature values and radiation dose in non-tumoral regions of the brain in paediatric brain tumours

BACKGROUND

Paediatric brain tumour survivors may have treatment toxicity associated with signal change on follow-up MRI. Quantitative MRI texture features can potentially be used as surrogates of the underlying tissue changes following radiation therapy.

MATERIAL AND METHODS

Longitudinal retrospective study in 51 paediatric primary brain tumours treated with photon (N=30) and proton (N=21) radiotherapy (RT). T2 MRI scans at baseline and multiple time point from the date of surgery to 2 years following radiotherapy were selected for the textural analysis. Scans were bias corrected, registered with the CT dose maps and with baseline scan for each patient using 3Dslicer. Regions of interest (ROI) of fixed diameter were drawn in 11 predetermined non-tumoral regions of brain including in peri-tumoural region (PTV). ROIs were placed in homogenous white/grey matter. Radiation dose was calculated in each of these 11 ROIs and texture features were extracted using pyradiomics. Data were analysed using machine learning and statistical analysis. General linear multivariate model was used to corelate primary texture features over period of 24 months and radiation dose, time, effect of dose*time together at each ROI separately.

RESULTS

There were Brainstem 4, Cerebellar19, Hemispheric cerebral 7 and Supratentorial midline 10 tumours. Median age at diagnosis was 8.26 years (range: 0–20). Median RT treatment dose was 28.52Gy (0-60Gy). Multivariate analysis shows significant corelation (p < 0.001) between radiation dose and longitudinal primary texture features in all 11ROIs. Time showed corelation with feature values only in 3 ROIs and dose* time showed corelation in 5ROIs. Primary (statistical) feature values showing consistent correlation with dose in all 11 ROIs over 24 months are total energy, 10%, 90%, energy, entropy, mean, median, and minimum.

CONCLUSION

Radiomic texture analysis is a promising modality to understand dose related textural changes in the normal part of brain in paediatric brain tumour patients treated with radiation therapy. Radiomic changes need to be related to neurological outcomes in future research.

P1731 Multiple floating thrombi in aortic arch leading to acute stroke: A case report and systematic review of literature

Introduction

Around 10-15% of acute cerebrovascular events occur in young adults with age less than 40 years. Trans-oesophageal echocardiogram (TOE) is routinely performed to rule out any cardio-embolic source in patients with ischemic stroke. TOE has shown to significantly change management strategy in up to 16.7% of stroke cases. We report a rare case of recurrent stroke in a young female who was found to have multiple mobile thrombi in aortic arch on TOE. We also report systematic review of literature of similar cases to highlight the management strategies.

Case Presentation

A 38-year-old female presented with one-week history of right upper and lower extremity paresthesia along with headache. Physical examination was unremarkable for any focal neurological deficits at time of initial evaluation. She had pertinent history of acute stroke two years ago associated with non-occlusive left common carotid artery thrombus for which she was previously on anticoagulation with rivaroxaban. The anticoagulation, however, was stopped five months ago after repeat imaging revealed complete resolution of thrombus. Electrocardiogram showed normal sinus rhythm without any other significant abnormality. CT head showed no acute bleeding or infarct. MRI brain showed scattered infarcts in right cerebral hemisphere and left cerebellar hemisphere. CT angiography of head and neck showed multiple small nodular and linear pedunculated thrombi in distal arch of aorta (see Figure 2). TOE was then performed which confirmed two pedunculated and mobile echogenic masses, largest measuring 0.9 x 0.6 cm, in the distal aortic arch (see Figure 1). TOE did not show intracardiac source of embolism. Laboratory testing for thrombophilia was negative for Factor V and Prothrombin gene mutation and heterozygous positive for Methylenetetrahydrofolate reductase (MTHFR)-677T gene. She was also found to have elevated homocysteine levels. She was restarted on anticoagulation with rivaroxaban.

Discussion and Conclusion

Young patients with stroke should undergo detailed investigation to rule out hypercoagulable pathology and cardiovascular embolic source. This should also include multimodality imaging including TOE in the selected patients. During TOE examination, a particular attention should be paid for evaluation of aortic source of thombo-embolism. Our patient was heterozygous for MTHFR-66T gene which is associated with decreassed activity of MTHFR by 35 % with elevated homocysteine levels. Treatment of floating aortic thrombus is still controversial. Anticoagulation is suggested as primary modality by multiple authors who reported complete resolution of thrombus. Other option includes surgical thrombectomy. Our patient was treated with anticoagulation alone due to hypercoagulable state and small size of thrombi.

Abstract P1731 Figure.

Calcitropic hormonal status in north Indian patients with end-stage renal disease

BACKGROUND

Bone disease in chronic renal failure has a wide spectrum that includes both high and low turnover conditions. Specific preventive and therapeutic measures require knowledge of the nature of bone involvement. Bone biopsy with static and dynamic histomorphometry is the gold standard for characterization of renal bone disease. However, non-invasive biochemical tests, especially serum intact parathyroid hormone (PTH), have a good correlation with histomorphometry. We studied the clinical and biochemical profile of bone disease in a sample of north Indian patients with chronic renal failure.

METHODS

Twenty-nine patients of chronic renal failure were evaluated clinically, radiologically (subperiosteal erosions on hand X-rays) and biochemically (serum calcium, phosphorus, total alkaline phosphatase, intact PTH, osteocalcin, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D). Bone histomorphometry could be done in 4 patients.

RESULTS

Serum intact PTH within or below the non-uraemic normal range, an index of low bone turnover, was seen in 17 (58.6%) patients. Serum osteocalcin, a bone formation marker, was within or below the non-uraemic normal range in 65.5% patients. Serum intact PTH and osteocalcin had a significant positive correlation (r = 0.6). Patient groups with clinical or radiological evidence of bone disease had serum intact PTH and osteocalcin levels comparable to those lacking such features. Serum intact PTH and total alkaline phosphatase were lower in haemodialysed (n = 25) patients than in those who had not received haemodialysis (n = 4). Low (< 10 ng/ml) serum 25-hydroxyvitamin D levels were seen in 7 (24%) patients while 1,25-dihydroxyvitamin D was low (< 15.9 pg/ml) in 20 (69%) patients. The biochemical parameters accurately reflected the bone histology (n = 4).

CONCLUSIONS

Our data show that the majority of north Indian patients with chronic renal failure have biochemical evidence of low bone turnover. Empirical use of calcium salts and active vitamin D analogues without documentation of parathyroid status carry the risk of further suppression of bone turnover.