Keith Chiu

Review of Direct Anatomical Open Surgical Management of Atherosclerotic Aorto-Iliac Occlusive Disease

BACKGROUND Aortofemoral bypass(AFB), iliofemoral bypass(IFB), and aortoiliac endarterectomy(AIE) are the three most common techniques for anatomical open surgical revascularisation for patients with aorto-iliac occlusive disease(AIOD), but the optimal method of reconstruction is unknown. AIMS To review and compare mortality, morbidity and short- and long-term patency rates for AFB, IFB and AIE in patients with AIOD reported in the English language literature METHODS A MEDLINE(1970-2007) and Cochrane Library search for articles relating to AFB, IFB, AIE and AIOD was undertaken. Studies were included if: a) patency rates based on life-tables were available, and b) patient/study characteristics were reported. RESULTS 29 studies(5738 patients) for AFB, 11 studies(778 patients) for IFB and 11 studies(1490 patients) for AIE were included. Operative mortality was 4.1% for AFB, 2.7% for IFB and 2.7% for AIE (p<0.0001). Systemic morbidity was 16.0% for AFB, 18.9% for IFB and 12.5% for AIE (p<0.05). Overall 5-year primary patency rates were 86.3%, 85.3% and 88.3% for AFB, IFB and AIE, respectively (p=NS). CONCLUSION Aorto-iliac endarterectomy was associated with significantly lower peri-operative morbidity and mortality rates compared with bypass grafting. All three techniques were equally effective in terms of long-term patency.

Acute aortic syndrome: CT findings

Acute aortic syndrome (AAS) is a constellation of potentially life-threatening acute aortic diseases. The spectrum includes penetrating atherosclerotic ulcer, intramural haematoma, dissection, and unstable thoracic aneurysm. AAS cannot be reliably diagnosed clinically and multidetector computed tomography (MDCT) has revolutionized the diagnosis and management of this group of conditions in the acute setting due to its availability, speed, and accuracy. The purpose of this review is to illustrate key MDCT findings of AAS. Imaging techniques, radiological findings, and common pitfalls are also discussed.

Pulmonary thromboembolism in liver transplantation: a retrospective review of the first 25 years

The evidence on the state of ‘haemostasis’ at the time of liver transplantation (LT) is conflicting, with recent publications that suggest a hypercoagulable state, in contrast to traditionally held views. These findings raise the issue of thrombo‐embolic complications after LT, an area of interest which has received little attention in recent published literature. We therefore conducted a retrospective review of our experience of 3000 liver transplants over 25 years. Our prospective transplant database was reviewed to find all patients who were suspected to have had a pulmonary embolism (PE) during or following LT. Paediatric transplants were excluded. A part of this database was cross referenced against hospital records to corroborate its accuracy. Clinical records of all these patients were reviewed and relevant aspects collated and analyzed. Following exclusion of the paediatric recipients, 2 149 adults were reviewed to find 36 patients in whom a PE was suspected (median age 49), 21 of whom were within 90 days of transplant (median duration 22 days). PE was ruled out in 10, unconfirmed in two, confirmed in eight patients; and in one, air embolism was found. All PEs occurred in hospital, but aetiology of liver failure was varied. Of note, two patients died of an on‐table PE and one patient of chronic rejection/disease recurrence (Primary Sclerosing Cholangitis). The remaining five are still alive (median survival of 65 months). Although thromboprophylaxis is now routine in our unit, its use in these patients could not be confirmed from records available. Fifteen PE were suspected and confirmed after 90 days from transplant (six within, and nine out with the first year). Acute PE in the setting of LT has an incidence rate in our series of 0.37% that would appear to be lower than previously reported and lower than one would expect after a ‘major complex’ category operation. This potentially suggests that the overall haemostatic function in these patients is still weighted towards hypocoagulation with the resultant risk of excessive bleeding. Aetiology of liver disease did not seem to confer a higher risk in our series. The prognosis after post‐operative PE appears good although sudden death due to an on‐table embolism is a rare but significant risk.

Vocal cord paresis following single-session high intensity focused ablation (HIFU) treatment of benign thyroid nodules: incidence and risk factors

Abstract Background: Vocal cord paresis (VCP) may occur following high intensity focused ultrasound (HIFU) of thyroid nodules. We hypothesised its occurrence relates to the distance of the focus point (FP) of the HIFU beams from the recurrent laryngeal nerve (RLN) and the thermal power that this point received. Their relationships were examined. Methods: One hundred and three patients who underwent HIFU for symptomatic benign thyroid nodule from October 2015 to March 2017 were analysed. All treatment images were captured and were later watched by 2 reviewers to identify three FPs closest to the tracheoesophageal groove (TEG) on transverse sonographic view. TEG was taken as the RLN position. After identifying these FPs, their distance (mm) from the TEG, thermal power (W) used and depth from skin (mm) were recorded. These parameters were compared between those with and without VCP. VCP was defined as a cord with reduced or no movement. Results: Four (3.9%) patients suffered from a unilateral VCP afterwards but they all recovered fully within 6 weeks. There were no significant differences in baseline characteristics and treatment efficacy between the two groups. The distance from TEG (OR = 1.706, 95%CI = 1.001 to 2.915, p = 0.050) was the only significant factor for VCP. None of the other variables including thermal power were significant. Conclusions: The incidence of VCP was 3.9% (4/103) and they completely recovered within 6 weeks. The distance between the FP and the TEG was the only related factor for VCP. The safe distance between FP and TEG should be ≥1.1 cm.

High-intensity focused ablation (HIFU) of single benign thyroid nodule rarely alters underlying thyroid function

Abstract Background: High intensity focused ultrasound (HIFU) is a promising ablation technique for benign thyroid nodules. However, its effect on underlying thyroid function remains unknown. We aimed to evaluate the 6 months changes in serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) after HIFU treatment. Methods: Eighty-three consecutive patients who underwent single HIFU ablation for symptomatic benign thyroid nodule were analysed. Eligible patients had serum TSH and FT4 checked before treatment (baseline), 1 week, 3 and 6 months following HIFU treatment. Primary endpoints were hypothyroidism (FT4 < 12 pmol/L) and hyperthyroidism (FT4 > 23 pmol/L) in the 6 months following treatment. To express extent of nodule ablation relative to the total gland volume, an ablation volume ratio was calculated by [(Ablated nodule volume/total thyroid volume)/(total thyroid volume)] × 100. Results: Relative to baseline, 1-week serum TSH significantly dropped (from 1.16 to 0.76 mIU/L, p < 0.001) while 1-week serum FT4 significantly rose (from 16.0 to 17.8 pmol/L, p < 0.001). However, 3- and 6-months TSH and FT4 did not changed significantly from baseline (p > 0.05). No patients developed hyperthyroidism while one (1.4%) developed hypothyroidism (FT4 = 11 pmol/L) at 3 months and 6 months. Interestingly, this patient had a previous lobectomy and an ablation volume ratio of 64.00%. Conclusions: Hypothyroidism following single HIFU ablation occurred rarely (1.4%) and resulted in little clinical relevance. Given that only one patient developed hypothyroidism following single HIFU ablation, it remains unclear how patients with different amount of parenchyma and relative extent of ablation may affect subsequent thyroid function.

Contrast sonovenography – Is this the answer to complex deep vein thrombosis imaging?

Background: Deep vein thrombosis (DVT) is a potentially fatal condition causing significant morbidity and mortality in the patient population. Ultrasound (USS) is the mainstay for detecting DVT. This can sometimes be difficult in hostile limbs due to factors such as large body habitus and oedema. This pilot study investigated contrast-enhanced ultrasound (CEUS) as a viable method to improve visualisation of the venous system of the lower limb. Methods: Patients at high risk for DVT were selected after an initial negative USS. A follow-up scan was performed 1 week later utilising standard B-mode imaging with a curvilinear 3–5 MHz transducer array. After the fundamental scan, intravenous Sonovue™ contrast was administered and visualisation of the proximal limb veins and visualisation gains in distance were mapped onto a proforma. Results: Twelve patients were selected. Visualisation was not improved in the common femoral vein (CFV) but increases in full visualisation were demonstrated in the femoral vein (FV) and popliteal vein (Pop V) from (n = 8) 67% and (n = 10) 83–100% in both veins, respectively. Significant gains in visualisation distance were observed in the posterior tibial vein (PTV) (p = 0.0005) and peroneal vein (Per V) (p = 0.02) with increased full visualisation of the Per V from (n = 3) 25% to (n = 7) 58%. Conclusion: CEUS is a viable and clinically safe method for increasing visualisation of the deep venous system. It has the potential to improve visualisation of the lower limb venous system, reducing follow-up costs and diagnostic uncertainty for patients and the clinician.

Self-expandable metal stent placement for malignant duodenal obstruction distal to the bulb.

Objective Self-expandable metal stents (SEMS) are widely used for the palliative management of malignant proximal gastroduodenal obstruction because of its low morbidity and mortality rates compared with surgical bypass. However, stent placement for duodenal obstruction beyond the first part of the duodenum is considered technically difficult and is not routinely performed. We report our experience with SEMS placement for these patients. Methods Between 2006 and 2015, 51 patients with unresectable or metastatic malignancy underwent SEMS placements under combined endoscopic and fluoroscopic guidance. Eighteen patients had intestinal obstruction distal to the duodenal bulb. Their demographics, technical and clinical outcomes, periprocedural morbidity and mortality, length of hospital stay, further interventions and overall survival were analysed. Results Out of the 18 cases, nine cases of intestinal obstruction were due to primary malignancy of the pancreas, three due to gastric malignancy, three from other locoregional cancers and three were the result of metastases. In 12 patients, the obstruction involved the second part (D2), in four the third part (D3) and in two the fourth part (D4) of the duodenum. A front-facing therapeutic gastroscope was used to visualize the duodenum before the stricture was crossed under direct vision and fluoroscopic guidance, with a catheter and guidewire, and a through-the-scope SEMS deployed using an ‘over-the-wire’ technique. Technical success rate was 89%. The mean gastric outlet obstruction scores improved from 0.63 to 2.57 (P<0.0001). Four patients died within 30 days of the procedure, although none of the deaths were procedure related. The median length of postprocedural hospital stay was 4 days and the median overall survival was 58 days.

Single-Session High-Intensity Focused Ultrasound Treatment for Persistent or Relapsed Graves Disease: Preliminary Experience in a Prospective Study

Purpose To evaluate the safety and efficacy of ultrasonography (US)-guided high-intensity focused ultrasound (HIFU) ablation as a treatment for medically refractory Graves disease (GD). Materials and Methods After ethics approval, a prospective trial (NCT02685514) was performed from November 2015 to February 2016. Thirty patients underwent ablation of the entire right and left thyroid lobes, with areas near the tracheal-esophageal groove and common carotid artery left unablated. Serum thyroid-stimulating hormone (TSH), free T4 (FT4), antithyroid autoantibodies, and TSH receptor (TSHR) antibody levels were evaluated afterward, and US color Doppler, US volumetry, and eye assessment were performed. The primary outcome was the 12-month relapse rate. Relapse referred to hyperthyroidism (FT4 > 23 pmol/L) afterward. Variables associated with relapse were analyzed by using binary logistic regression. Results The technical success rate was 96.7%. The cohort comprised entirely women, with a median age of 38.2 years (interquartile range, 29.5-49.0 years). After 12 months, eight patients (26.7%; 95% confidence interval [CI]: 14.19%, 44.95%) experienced relapse. One patient (3.3%; 95% CI: 0.59%, 16.67%) experienced vocal cord palsy, while two patients (6.7%; 95% CI: 1.85%, 21.33%) experienced Horner syndrome, but none of these conditions were permanent. No changes in gland volume, antithyroid autoantibody levels, and ophthalmic parameters were found at 12-month follow-up. Baseline TSHR was found to have decreased significantly at 6- and 12-month follow-up (P < .001 for both). TSHR antibody (odds ratio [OR] = 1.414; 95% CI: 1.018, 1.965; P = .039) and gland volume (OR = 0.557; 95% CI: 0.353, 0.880; P = .012) were associated with 12-month relapse, with higher antibody levels conferring a higher likelihood and smaller gland volumes conferring a lower likelihood. Conclusion US-guided HIFU of the thyroid may be a safe and efficacious treatment in patients with persistent or relapsed GD. However, further study is warranted before it can become mainstream for this indication.

Association Patterns of Ontological Features Signify Electronic Health Records in Liver Cancer

Electronic Health Record (EHR) system enables clinical decision support. In this study, a set of 112 abdominal computed tomography imaging examination reports, consisting of 59 cases of hepatocellular carcinoma (HCC) or liver metastases (so-called HCC group for simplicity) and 53 cases with no abnormality detected (NAD group), were collected from four hospitals in Hong Kong. We extracted terms related to liver cancer from the reports and mapped them to ontological features using Systematized Nomenclature of Medicine (SNOMED) Clinical Terms (CT). The primary predictor panel was formed by these ontological features. Association levels between every two features in the HCC and NAD groups were quantified using Pearsons correlation coefficient. The HCC group reveals a distinct association pattern that signifies liver cancer and provides clinical decision support for suspected cases, motivating the inclusion of new features to form the augmented predictor panel. Logistic regression analysis with stepwise forward procedure was applied to the primary and augmented predictor sets, respectively. The obtained model with the new features attained 84.7% sensitivity and 88.4% overall accuracy in distinguishing HCC from NAD cases, which were significantly improved when compared with that without the new features.

PET/CT in the evaluation of treatment response to neoadjuvant chemoradiotherapy and prognostication in patients with locally advanced esophageal squamous cell carcinoma

ObjectiveTo investigate the role of fluorine-18-fluorodeoxyglucose PET/computed tomography for the prognostication and evaluation of neoadjuvant chemoradiotherapy response in locally advanced esophageal squamous cell carcinoma. MethodsAll consecutive biopsy-proven esophageal squamous cell carcinoma patients with PET/computed tomography at baseline (PET0) and 1 month after the completion of neoadjuvant chemoradiotherapy (PET1) between January 2008 and December 2013, followed by esophagectomy, were included. Maximum and mean standard uptake values (SUVmax and SUVmean), metabolic tumor volume, and total lesion glycolysis of all lesions at PET0 and PET1 were analyzed. Logistic and Cox regressions were used to identify factors predictive of pathological complete remission (pCR), overall survival, and recurrence-free survival. Cut-offs were identified using leave-one-out cross-validation adjusted receiver operator curve-based methods. A Kaplan–Meier model was adopted to compare survivals between groups using log-rank tests. ResultsOf a total of 52 patients (45 men, age 21–78 years), pCR was achieved in 21 (40.4%). SUVmax of primary tumor at PET1 was independently predictive of pCR [P=0.013, odds ratio=0.736, 95% confidence interval (CI): 0.578–0.937]; using a leave-one-out cross-validation-adjusted cut-off of 2.7, pCR could be predicted with a sensitivity of 71.0%, a specificity of 66.7%, a positive predictive value of 75.9%, and a negative predictive value of 60.9%. In the subset of 40 patients with standardized treatment included in survival analysis, total lesion glycolysis (P=0.002, hazard ratio: 1.029, 95% CI: 1.01–1.048) and SUVmax (P=0.003, hazard ratio: 1.167, 95% CI: 1.055–1.290) of nodal metastasis at PET0 were independently predictive of overall survival and recurrence-free survival, respectively. ConclusionBaseline total lesion glycolysis and SUVmax of nodal metastases are significant independent predictors of survival, whereas post-treatment SUVmax of the primary tumor is predictive of pCR. However, the predictive value of the latter is modest, which may limit its clinical utility.