Hong Kuan Kok

Multimodality imaging features of hereditary multiple exostoses

Hereditary multiple exostoses (HME) or diaphyseal aclasis is an inherited disorder characterised by the formation of multiple osteochondromas, which are cartilage-capped osseous outgrowths, and the development of associated osseous deformities. Individuals with HME may be asymptomatic or develop clinical symptoms, which prompt imaging studies. Different modalities ranging from plain radiographs to cross-sectional and nuclear medicine imaging studies can be helpful in the diagnosis and detection of complications in HME, including chondrosarcomatous transformation. We review the role and imaging features of these different modalities in HME.

Systematic Review and Single-Center Experience for Endovascular Management of Visceral and Renal Artery Aneurysms

PURPOSE To report a systematic review of endovascular management of visceral and renal artery aneurysms (VRAA) and results at a tertiary referral center. MATERIALS AND METHODS A literature review was performed via a comprehensive electronic search of PubMed, MEDLINE, EMBASE, and Cochrane databases, followed by retrospective analysis of all VRAAs treated at a tertiary referral center from January 1999 to December 2015. RESULTS The systematic review included 22 studies published between 2005 and 2016 describing endovascular treatment of VRAA. In the systematic review cohort, 646 aneurysms (432 true, 151 false, 63 unclassified) were treated using endovascular methods with 93.2% technical success, 99.3% visceral preservation, 3.5% major complication (classified based on Society of Interventional Radiology criteria), 1.5% 30-day periprocedural mortality, and 4.6% reintervention rates. In the local cohort, 19 aneurysms (12 true, 7 false) were treated with 100% technical success, 94.7% visceral preservation, and 10.5% major complication rates. There was no periprocedural mortality. Over mean follow-up of 31.9 months (range, 2-170 months), there were 2 aneurysm reperfusions, which required no further treatment. Results incorporating data from the systematic review and local cohorts (665 aneurysms) showed 93.6% technical success, 99.1% visceral preservation, 3.7% major complication, 1.5% periprocedural mortality, and 4.4% reintervention rates. CONCLUSIONS Endovascular treatment of VRAA is associated with excellent technical success and visceral preservation rates. Major complication and periprocedural mortality rates are comparatively low. A few VRAA (4.4%) required future reintervention suggesting that imaging follow-up is essential after initial treatment.

Retrievable IVC filters - Friend or foe.

Venous thromboembolism is a common condition with widely varied outcomes. Pulmonary embolism is associated with a case-fatality rate of up to 8%, increasing up to 18-fold in massive PE. Pharmacological treatment of VTE with anticoagulant medication (AC) is the first line therapy of choice. Retrievable inferior vena cava filters (IVCF) are indicated as a short-term replacement for AC in certain circumstances. Most of the evidence concerning IVCF pertains to permanent filters and older filter models. Limited evidence for retrievable IVCF results in poor consensus regarding indications, follow-up and retrieval. Complications increase with dwell-time and retrieval success rates decline. Professional bodies advocate strict guideline adherence and robust strategies for filter monitoring to maximise retrieval rate.

Current evidence for endovascular therapy in stroke and remaining uncertainties

Class 1 level A evidence now supports endovascular thrombectomy as best practice in the management of large vessel occlusion acute ischaemic stroke. However, significant questions pertaining to initial imaging, radiological assessment, patient selection and therapeutic limits remain unanswered. A specific cohort of patients who benefit from endovascular thrombectomy has been established, although current uncertainties regarding selection of those not meeting top‐tier evidence criteria may potentially deny certain patients the benefit of intervention. This is of particular relevance in patients presenting in a delayed manner. Whilst superior outcomes are achieved with reduced time to endovascular reperfusion, denying patients intervention based on symptom duration alone may not be appropriate. Advanced understanding of ischaemic stroke pathophysiology supports an individualized approach to patient evaluation, given variance in the rate of ischaemic core progression and the extent of salvageable penumbra. Physiological imaging techniques may therefore be utilized to better inform patient selection for endovascular thrombectomy and evidence suggests that a transition from time‐based to tissue‐based therapeutic thresholds may be of greater value. Multiple ongoing randomized controlled trials aim to further define the benefit of endovascular thrombectomy and it is hoped that these results will advance, and possibly broaden, patient selection criteria to ensure that maximum benefit from the intervention may be achieved.

Outcomes of endovascular treatment for acute large‐vessel ischaemic stroke more than 6 h after symptom onset

Benefit from endovascular thrombectomy (EVT) for large‐vessel occlusion (LVO) acute ischaemic stroke (AIS) is well demonstrated. Furthermore, emerging evidence supports efficacy in appropriately selected patients treated beyond current recommendations of 6 h. We evaluated clinical outcomes in patients undergoing late EVT at our institution.

Reducing risk of transjugular intrahepatic portosystemic shunt using ultrasound guided single needle pass

Delayed liver laceration following transjugular intrahepatic portosystemic shunt (TIPS) is a serious and likely underdiagnosed complication. It is however an important complication following TIPS, which remains one of the most technically challenging interventional procedures performed. In addition to laceration, a number of complications regarding bleeding and perforation are well described following TIPS procedures. We feel the adoption of techniques such as ours and that of other authors described in the literature using an ultrasound-guided percutaneous transhepatic approach with a small caliber needle provides a safer and less traumatic procedure and should reduce complications of bleeding and almost completely eliminate the risk of liver laceration. Our procedure was successfully performed under conscious sedation rather than general anaesthesia further reducing the overall procedural risk to the patient.

Outcomes of infrapopliteal angioplasty for limb salvage based on the updated TASC II classification

PURPOSE We aimed to evaluate limb salvage, defined as freedom from major amputation, and to identify predictors of major amputation in patients with infrapopliteal peripheral arterial disease (PAD) based on the updated 2015 TASC II anatomic classification treated by percutaneous transluminal angioplasty (PTA). METHODS This was a retrospective study of infrapopliteal PTA procedures performed for PAD over a 4-year period. Patient demographics, medical comorbidities, risk factors, angiographic imaging, technical details, and clinical follow-up were analyzed to determine limb salvage rates, technical success, and all-cause mortality. Predictors of major amputation following PTA were identified. RESULTS A total of 112 patients were treated by infrapopliteal PTA. Most lesions consisted of TASC C (44%) and D (34%) categories, were over 10 cm in length, and were occlusive and heavily calcified (89%). Overall technical success was 75%, with limb salvage rates of 77% at 1 year and 65% at 3 years following PTA. Smoking, previous stroke or cardiovascular events, and anticoagulation use were associated with an increased risk of major amputation following PTA. CONCLUSION PTA of complex infrapopliteal PAD is associated with good intermediate term limb salvage rates.

The 100 most cited articles in the endovascular management of intracranial aneurysms

Introduction Endovascular interventions for intracranial aneurysms have evolved substantially over the past several decades. A citation rank list is used to measure the scientific and/or clinical impact of an article. Our objective was to identify and analyze the characteristics of the 100 most cited articles in the field of endovascular therapy for intracranial aneurysms. Methods We performed a retrospective bibliometric analysis between July and August 2017. Articles were searched on the Science Citation Index Expanded database using Web of Science in order to identify the most cited articles in the endovascular therapy of intracranial aneurysms since 1945. Using selected key terms (‘intracranial aneurysm’, ‘aneurysm’, ‘aneurysmal subarachnoid’, ‘endovascular’, ‘coiling’, ‘stent-assisted’, ‘balloon-assisted’, ‘flow-diversion’) yielded a total of 16 314 articles. The top 100 articles were identified and analyzed to extract relevant information, including citation count, authorship, article type, subject matter, institution, country of origin, and year of publication. Results Citations for the top 100 articles ranged from 133 to 1832. All articles were cited an average of 27 times per year. There were 45 prospective studies, including 7 level–II randomized controlled trials. Most articles were published in the 2000s (n=53), and the majority constituted level III or level IV evidence. Half of the top 100 articles arose from the USA. Conclusion This study provides a comprehensive overview of the most cited articles in the endovascular management of intracranial aneurysms. It recognizes the contributions made by key authors and institutions, providing an important framework to an enhanced understanding of the evidence behind the endovascular treatment of aneurysms.

Neuroimaging of chronic alcohol misuse.

Alcohol is one of the most commonly abused substances worldwide. It results in a wide range of diseases and disorders affecting many organ systems. Alcohol‐related nutritional deficiencies and electrolyte disturbance leave chronic abusers at risk of a range of demyelinating conditions to which the radiologist and clinician should always be alert. These include Wernickes encephalopathy, Korsakoffs syndrome, Marchiafava‐Bignami disease and osmotic demyelination. Cerebral volume loss is also a commonly encountered neuroimaging phenomenon in chronic alcohol abusers. Neuroimaging with CT and MR, with a focus on FLAIR and diffusion‐weighted MR sequences, play an important role in the diagnosis and often monitoring of these conditions. We present an educational review of these entities in terms of their clinical features, neuropathology and imaging features along with a case example of each condition.

Endovascular Treatment of Wide-Necked Visceral Artery Aneurysms Using the Neurovascular Comaneci Neck-Bridging Device: A Technical Report.

IntroductionVisceral and renal artery aneurysms (VRAAs) are an uncommon clinical entity but carry a risk of rupture with associated morbidity and mortality. The rupture risk is particularly high when the aneurysms are large, of unfavourable morphology or in the setting of pregnancy and perioperative period. Endovascular approaches are now first line in the treatment of VRAA, but conventional techniques may be ineffective in excluding aneurysms with unfavourable anatomy such as those with wide necks or at arterial bifurcation points. The neurovascular Comaneci neck-bridging device is used to temporarily cover the neck of intracranial aneurysms without occluding forward arterial flow during endovascular coiling. We report the novel use of the Comaneci neck-bridging device for the treatment of complex peripheral VRAAs.Materials and MethodsWe describe the treatment of two patients with renal and splenic artery aneurysms demonstrating unfavourable anatomic morphology for conventional endovascular approaches.ResultsIn the first patient, the renal artery aneurysm was situated at the intrarenal bifurcation of the main renal artery in the setting of a solitary kidney. In the second patient, the splenic artery aneurysm was situated close to the splenic hilum at the distal splenic arterial bifurcation. The Comaneci neck-bridging device was successfully used in both cases to assist coil embolisation with visceral preservation.ConclusionsThe Comaneci neck-bridging device is potentially safe and effective for the treatment of peripheral VRAA with unfavourable anatomic characteristics that would have been deemed unsuitable for treatment using conventional techniques.Level of EvidenceLevel 4, Technical Report.