Two-year clinical outcomes following lower limb endovascular revascularisation for chronic limb-threatening ischaemia at a tertiary Asian vascular centre in Singapore

INTRODUCTION@#Percutaneous transluminal angioplasty (PTA) is commonly used to treat patients with chronic limb-threatening ischaemia (CLTI). This study aimed to examine the mortality and functional outcomes of patients with CLTI who predominantly had diabetes mellitus in a multi-ethnic Asian population in Singapore.@*METHODS@#Patients with CLTI who underwent PTA between January 2015 and March 2017 at the Vascular Unit at Singapore General Hospital, Singapore, were studied. Primary outcome measures were 30-day unplanned readmission, two-year major lower extremity amputation (LEA), mortality rates, and ambulation status at one, six and 12 months.@*RESULTS@#A total of 221 procedures were performed on 207 patients, of whom 184 (88.9%) were diabetics. The one-, six- and 12-month mortality rate was 7.7%, 16.4% and 21.7%, respectively. The two-year LEA rate was 30.0%. At six and 12 months, only 96 (46.4%) and 93 (44.9%) patients were ambulant, respectively. Multivariate analysis revealed that preoperative ambulatory status, haemoglobin, Wound Ischaemia and foot Infection (WIfI) score, and end-stage renal failure (ESRF) were independent predictors of one-year ambulatory status. Predictors of mortality at one, six and 12 months were ESRF, preoperative albumin level, impaired functional status and employment status.@*CONCLUSION@#PTA for CLTI was associated with low one-year mortality and two-year LEA rates but did not significantly improve ambulation status. ESRF and hypoalbuminaemia were independent predictors of mortality. ESRF/CKD and WIfI score were independent predictors of loss of ambulation at six months and one year. We need better risk stratification for patients with CLTI to decide between initial revascularisation and an immediate LEA policy.

Distribution of Peripheral Arterial Disease in Patients Undergoing Endovascular Revascularization for Chronic Limb Threatening Ischaemia: Insights from the Vascular Quality Initiative in Singapore

This study aimed to examine the distribution of lower limb atherosclerotic lesions in a multi-ethnic Asian cohort with chronic limb threatening ischemia (CLTI) from Singapore. The Society for Vascular Surgery Vascular Quality Initiative registry database was used to identify 265 CLTI patients who underwent percutaneous angioplasty between June 2019 and December 2019, of whom 171 (64.5%) were male, and the mean age was 67.9±11.0 years. The majority were diabetic (84.5%) and 145 (54.7%) had chronic kidney disease (CKD). The majority of the lower limb atherosclerotic lesions were de novo lesions (598/797, 75.0%), predominantly TransAtlantic Inter-Society Consensus II C/D (451/797, 56.6%), and were moderately to severely calcified (76.3%). The anterior tibial artery and femoral-popliteal artery were the most commonly affected vessels. The mean length of the treated lesions was 14.5±13.7 cm. There was a tendency, albeit insignificant, of multi-level disease in those who were diabetic or had CKD.

Distribution of Peripheral Arterial Disease in Patients Undergoing Endovascular Revascularization for Chronic Limb Threatening Ischaemia: Insights from the Vascular Quality Initiative in Singapore

This study aimed to examine the distribution of lower limb atherosclerotic lesions in a multi-ethnic Asian cohort with chronic limb threatening ischemia (CLTI) from Singapore. The Society for Vascular Surgery Vascular Quality Initiative registry database was used to identify 265 CLTI patients who underwent percutaneous angioplasty between June 2019 and December 2019, of whom 171 (64.5%) were male, and the mean age was 67.9±11.0 years. The majority were diabetic (84.5%) and 145 (54.7%) had chronic kidney disease (CKD). The majority of the lower limb atherosclerotic lesions were de novo lesions (598/797, 75.0%), predominantly TransAtlantic Inter-Society Consensus II C/D (451/797, 56.6%), and were moderately to severely calcified (76.3%). The anterior tibial artery and femoral-popliteal artery were the most commonly affected vessels. The mean length of the treated lesions was 14.5±13.7 cm. There was a tendency, albeit insignificant, of multi-level disease in those who were diabetic or had CKD.

Single-centre retrospective review of risk factors for local tumour progression and complications in radiofrequency ablation of 555 hepatic lesions

INTRODUCTION@#This study aimed to assess safety, local tumour progression (LTP) and risk factors for LTP after radiofrequency ablation (RFA) of liver tumours in a single centre.@*METHODS@#All consecutive patients treated with RFA for liver tumours between January 2009 and October 2012 were included. Previously treated lesions that progressed were excluded. Using electronic medical records, the following data was captured: patient demographics, pre-procedural laboratory results, Child-Pugh status, tumour characteristics, development of tumoral seeding, RFA complications and LTP. Possible risk factors for LTP were identified using Cox regression.@*RESULTS@#In total, 555 liver tumours were treated in 337 patients. 483 (87.0%) hepatocellular carcinomas, 52 (9.4%) colorectal metastases and 20 (3.6%) other tumour types were treated. Mean tumour size was 2.1 ± 1.1 (range 0.4-6.8) cm. Mean follow-up duration was 387 days. 416 (75.0%) lesions had no LTP at the last imaging. 70 (12.6%) patients had minor complications requiring observation, while 7 (1.3%) patients had significant complications requiring prolonged hospitalisation or further interventions. Only one case of tumour seeding was detected. Using multivariate Cox regression, the following factors were statistically significant in predicting LTP: hilar location (relative ratio [RR] 3.988), colorectal metastases (RR 2.075), size (RR 1.290) and younger age (RR 0.982).@*CONCLUSION@#RFA of liver tumours is safe and effective, with a low significant complication rate of 1.3%. Hilar lesions are most prone to LTP, followed by lesions that were larger in size and colorectal metastases. 75.0% of patients showed no LTP at the last follow-up.

A practical and adaptive approach to lung cancer screening: a review of international evidence and position on CT lung cancer screening in the Singaporean population by the College of Radiologists Singapore

Lung cancer is the leading cause of cancer-related death around the world, being the top cause of cancer-related deaths among men and the second most common cause of cancer-related deaths among women in Singapore. Currently, no screening programme for lung cancer exists in Singapore. Since there is mounting evidence indicating a different epidemiology of lung cancer in Asian countries, including Singapore, compared to the rest of the world, a unique and adaptive approach must be taken for a screening programme to be successful at reducing mortality while maintaining cost-effectiveness and a favourable risk-benefit ratio. This review article promotes the use of low-dose computed tomography of the chest and explores the radiological challenges and future directions.

Application of a standardised protocol for hepatic venous pressure gradient measurement improves quality of readings and facilitates reduction of variceal bleeding in cirrhotics

<p><b>INTRODUCTION</b>Hepatic venous pressure gradient (HVPG) measurement is recommended for prognostic and therapeutic indications in centres with adequate resources and expertise. Our study aimed to evaluate the quality of HVPG measurements at our centre before and after introduction of a standardised protocol, and the clinical relevance of the HVPG to variceal bleeding in cirrhotics.</p><p><b>METHODS</b>HVPG measurements performed at Singapore General Hospital from 2005-2013 were retrospectively reviewed. Criteria for quality HVPG readings were triplicate readings, absence of negative pressure values and variability of ≤ 2 mmHg. The rate of variceal bleeding was compared in cirrhotics who achieved a HVPG response to pharmacotherapy (reduction of the HVPG to < 12 mmHg or by ≥ 20% of baseline) and those who did not.</p><p><b>RESULTS</b>126 HVPG measurements were performed in 105 patients (mean age 54.7 ± 11.4 years; 55.2% men). 80% had liver cirrhosis and 20% had non-cirrhotic portal hypertension (NCPH). The mean overall HVPG was 13.5 ± 7.2 mmHg, with a significant difference between the cirrhosis and NCPH groups (p < 0.001). The proportion of quality readings significantly improved after the protocol was introduced. HVPG response was achieved in 28 (33.3%, n = 84) cirrhotics. Nine had variceal bleeding over a median follow-up of 29 months. The rate of variceal bleeding was significantly lower in HVPG responders compared to nonresponders (p = 0.025).</p><p><b>CONCLUSION</b>The quality of HVPG measurements in our centre improved after the introduction of a standardised protocol. A HVPG response can prognosticate the risk of variceal bleeding in cirrhotics.</p>

Competency-based Radiology Residency: A Survey of Expectations from Singapore's Perspective

In response to the demands of an ageing nation, the postgraduate medical education in Singapore is currently in the early stage of transition into the American-styled residency programme. This study assessed the expectations of both radiology trainees and faculty on their ideal clinical learning environment (CLE) which facilitates the programme development. A modified 23-item questionnaire was administered to both trainees and faculty at a local training hospital. All items were scored according to their envisioned level of importance and categorised into 5 main CLE domains-supervision, formal training programme, work-based learning, social atmosphere and workload. 'Supervision' was identified as the most important domain of the CLE by both trainees and faculty, followed by 'formal training programmes', 'work-based learning' and 'social atmosphere'. 'Workload' was rated as the least important domain. For all domains, the reported expectation between both trainees and faculty respondents did not differ significantly. Intragroup comparison also showed no significant difference within each group of respondents. This study has provided valuable insights on both respondents' expectations on their ideal CLE that can best train competency in future radiologists. Various approaches to address these concerns were also discussed. The similarities in findings between ours and previous studies suggest that the 'supervision', 'formal training programmes' and 'work-based learning' domains are crucial for the success of a postgraduate medical training and should be emphasised in future curriculum. 'Workload' remains a challenge in postgraduate medical training, but attempts to address this will have an impact in future radiology training.

Percutaneous transluminal angioplasty of transplant renal artery stenosis

<p><b>INTRODUCTION</b>This study aimed to assess the outcome of percutaneous transluminal angioplasty (PTA) as the primary treatment for transplant renal artery stenosis (TxRAS).</p><p><b>MATERIALS AND METHODS</b>A retrospective review of PTA of TxRAS from April 1999 to December 2008 was performed. Twenty-seven patients (17 males (M):10 females (F)) with the mean age of 49.5 years underwent PTA of TxRAS in the review period. Indications for PTA were suboptimal control of hypertension (n=12), impaired renal function (n=6) and both suboptimal control of hypertension and impaired renal function (n=9). All patients had doppler ultrasound scans prior to their PTA. In addition, 5 of these patients had computed tomography angiography (CTA) and another 7 had magnetic resonance angiography (MRA) evaluation. Mean follow-up period was 57.0 months (range, 7 to 108 months).</p><p><b>RESULTS</b>The stenotic lesions were located proximal to the anastomosis (n=2), at the anastomosis (n=15), and distal to the anastomosis (n=14). Technical success rate was 96.3%. One case was complicated by extensive dissection during PTA, resulting in subsequent graft failure. The overall clinical success rate was 76.9%. Seven out of 26 patients had restenoses (26.9% of cases). These were detected at a mean of 14.3 months post angioplasty (range, 5 to 38 months). All 7 patients underwent a second PTA successfully. Three of these patients required more than 1 repeat PTA.</p><p><b>CONCLUSION</b>PTA is safe and effective in the management of symptomatic TxRAS and should be the primary treatment of choice. Close surveillance for restenosis is required and when diagnosed, re-angioplasty can be performed.</p>

Single centre experience of transjugular liver biopsy in 152 patients

<p><b>INTRODUCTION</b>Liver biopsy is considered the definitive investigation in the diagnosis and management of liver disease. This study describes the experience of performing transjugular liver biopsy (TJLB) over the last 9 years in a local single centre.</p><p><b>MATERIALS AND METHODS</b>A retrospective review of consecutive TJLB procedures performed at our institution was conducted. A total of 152 patients (74 males and 78 females), with a mean age of 47.4 years (range, 13 to 83 years) underwent a total of 154 TJLB procedures at our institution between March 2003 and November 2011. The principal indication for TJLB was severe coagulopathy in over 80% of patients. The technical success, number of passes, histological adequacy and complication rates were analysed.</p><p><b>RESULTS</b>The procedural success rate was 98.7% (152 out of 154 procedures). Adequate material for diagnosis was obtained in 149 out of 152 (98.0%) technically successful procedures. There was procedure related morbidity in 8 patients (5.2%) of which all but one were self-limiting requiring no further intervention. We also performed hepatic venous pressure gradient (HVPG) measurements in 19% of patients at the time of TJLB.</p><p><b>CONCLUSION</b>TJLB performed at our institution is a safe and reliable technique in patients in whom traditional percutaneous liver biopsy may be hazardous. TJLB has a high technical success rate as well as a high diagnostic yield with a low complication rate. TJLB also has the added benefit of performing HVPG, which is of increasing importance in management and prognostication of chronic liver disease.</p>

Duplex ultrasonography arteriography as first-line investigation for peripheral vascular disease

<p><b>INTRODUCTION</b>The gold standard for evaluation of the lower extremity arterial tree is catheter angiography. Duplex arterial-occlusive imaging or duplex ultrasonography arteriography, a noninvasive technique, is used as the first-line investigation in patients with peripheral vascular disease at our centre. Based on the results of duplex imaging, patients who require angiographic intervention then proceed with simultaneous catheter arteriography and intervention. This study aimed to compare the results of duplex imaging alone as the first-line investigation against the eventual results of catheter angiography, and to assess the impact of the former on patients' clinical outcomes.</p><p><b>METHODS</b>All cases involving patients who underwent duplex imaging followed by angiographic intervention, from May 2008 to February 2009, were discussed at weekly interdisciplinary meetings. Only patients who underwent lower limb imaging were included in the study. Those who were involved in grafts and stent surveillance studies, as well as those with incomplete duplex images were excluded.</p><p><b>RESULTS</b>During the study period, 113 duplex imaging studies of the lower limb followed by percutaneous transluminal angioplasty were performed at our hospital for peripheral vascular disease. The iliac artery was visualised in 40 images, but could not be visualised in 73 images. There was a potential change in management in three cases due to radiological differences between the duplex images and angiography films.</p><p><b>CONCLUSION</b>In our series, duplex imaging was found to be accurate enough to guide initial clinical management of patients with peripheral vascular disease. This modality is the preferred first-line investigation for such patients at our centre.</p>

C-arm Cone Beam Computed Tomography: A New Tool in the Interventional Suite

<p><b>INTRODUCTION</b>C-arm Cone Beam CT (CBCT) is a technology that is being integrated into many of the newer angiography systems in the interventional suite. Due to its ability to provide cross sectional imaging, it has opened a myriad of opportunities for creating new clinical applications. We review the technical aspects, current reported clinical applications and potential benefits of this technology.</p><p><b>MATERIALS AND METHODS</b>Searches were made via PubMed using the string "CBCT", "Cone Beam CT", "Cone Beam Computed Tomography" and "C-arm Cone Beam Computed Tomography". All relevant articles in the results were reviewed.</p><p><b>RESULTS</b>CBCT clinical applications have been reported in both vascular and non-vascular interventions. They encompass many aspects of a procedure including preprocedural planning, intraprocedural guidance and postprocedural assessment. As a result, they have allowed the interventionalist to be safer and more accurate in performing image guided procedures. There are however several technical limitations. The quality of images produced is not comparable to conventional computed tomography (CT). Radiation doses are also difficult to quantify when compared to CT and fluoroscopy.</p><p><b>CONCLUSION</b>CBCT technology in the interventional suite has contributed significant benefits to the patient despite its current limitations. It is a tool that will evolve and potentially become an integral part of imaging guidance for intervention.</p>

Cone beam computed tomography for vascular interventional radiology procedures: early experience

<p><b>INTRODUCTION</b>Cone beam computed tomography (CBCT) is a relatively new technological innovation that utilises fl at-panel detector technology to obtain CT-like images. The key strength of a CBCT system is that cross-sectional imaging can be obtained using the angiographic fl at panel unit without having to move the patient, allowing the radiologist to obtain soft tissue imaging during the procedure. This allows treatment planning, guidance, and assessment of outcome to be performed in one interventional suite.</p><p><b>MATERIALS AND METHODS</b>From December 2008 to June 2009, 24 CBCT scans were performed during vascular interventional procedures on our department's newly installed multi-axis fl at panel angiographic unit.</p><p><b>RESULTS</b>Ten cases were performed for hepatic trans-arterial chemoembolisation, 9 cases for hepatic arterial Yttrium-90 infusion, while 5 cases were for other indications. CBCT was found to be useful in 20 of the 24 cases.</p><p><b>CONCLUSION</b>Our early experience showed that CBCT was useful in impacting decisions during selected vascular interventional procedures. As CBCT technology improves, we can foresee wider applications of this technology.</p>