Imperial College London

Mr Daniel Richard Leff

Faculty of MedicineDepartment of Surgery & Cancer

Reader in Breast Surgery
 
 
 
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Contact

 

+44 (0)20 3312 1947d.leff

 
 
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Location

 

Queen Elizabeth the Queen Mother Wing (QEQM)St Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

163 results found

Leff DR, Lovegrove RE, Darzi LA, Athanasiou Tet al., 2010, Data collection, database development and quality control: Guidance for clinical research studies, Key Topics in Surgical Research and Methodology, Pages: 305-320, ISBN: 9783540719144

Data collection is fundamental to any clinical surgical research study. Without collecting reliable and accurate data, it is impossible to draw meaningful conclusions regarding the research question of interest. This chapter aims to provide an overview of how to plan generic data collection and data storage, protocols, training and analysis that promote accurate and reliable data collection. Additionally, the fundamentals of database models and storage are covered to aid the novice researcher. A wealth of more detailed database design information and administration is available elsewhere for those who wish to pursue more complex designs. Throughout this chapter, we illustrate principles explained using clinically relevant examples. © Springer-Verlag Berlin Heidelberg 2010.

Book chapter

Leff DR, Orihuela-Espina F, Athanasiou T, Karimyan V, Elwell CE, Yang G-Z, Darzi AWet al., 2010, Decoupling neurocognitive and technical performance in sleep deprived surgical residents through longitudinal analyses of cortical brain function: Advancing our understanding of compensation to acute fatigue, Annual Clinical Congress of American-College-of-Surgeons, Publisher: ELSEVIER SCIENCE INC, Pages: S118-S118, ISSN: 1072-7515

Conference paper

Orihuela-Espina F, Leff DR, James DRC, Darzi AW, Yang GZet al., 2010, Quality control and assurance in functional near infrared spectroscopy (fNIRS) experimentation, Physics in Medicine and Biology, Vol: 55, Pages: 3701-3724, ISSN: 1361-6560

Journal article

Leff DR, James DRC, Orihuela-Espina F, Yang G-Z, Darzi AWet al., 2010, The frontal cortex is activated during learning of endoscopic procedures (Ohuchida et al., Surgical Endoscopy, January 2009), SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES, Vol: 24, Pages: 968-969, ISSN: 0930-2794

Journal article

Najefi A, Leff DR, Nicolaou M, Nduka C, Yang G-Z, Darzi AWet al., 2010, Monitoring of Free Flaps Using Near-Infrared Spectroscopy: A Systematic Review of the Initial Trials, PLASTIC AND RECONSTRUCTIVE SURGERY, Vol: 125, Pages: 182E-184E, ISSN: 0032-1052

Journal article

Unadkat SN, Leff DR, Teoh T-G, Rai R, Darzi AW, Ziprin Pet al., 2010, Anorectal symptoms during pregnancy: how important is trimester?, INTERNATIONAL JOURNAL OF COLORECTAL DISEASE, Vol: 25, Pages: 375-379, ISSN: 0179-1958

Journal article

Saso S, Vecht JA, Rao C, Protopapas A, Ashrafian H, Leff D, Darzi A, Athanasiou Tet al., 2010, Statin therapy may influence the incidence of postoperative atrial fibrillation: what is the evidence?, Texas Heart Institute Journal, Vol: 36, Pages: 521-529, ISSN: 1526-6702

Atrial fibrillation is the most common postoperative arrhythmia in patients who undergo cardiac surgery. We sought to determine whether the administration of statins reduces the incidence of postoperative atrial fibrillation in cardiac surgery patients. We performed a meta-analysis on all studies published between 2004 and 2008 that reported comparisons between statin treatment or nontreatment in these patients. Our primary focus was the incidence of postoperative atrial fibrillation. Random-effects modeling and sensitivity analysis were used to evaluate the consistency of the calculated treatment effect. Ten qualifying studies generated a total of 4,459 patients. The incidence of postoperative atrial fibrillation was 22.6% (622/2,758) in the statin-treated group and 29.8% (507/1,701) in the untreated group. Using the random-effects model, we calculated an odds ratio (OR) of 0.60 (95% confidence interval [CI], 0.48-0.76). When we considered only the 4 randomized studies (919 patients) in order to reduce the effects of heterogeneity, this significant reduction in the incidence of postoperative atrial fibrillation in the statin group was maintained (OR, 0.55; 95% CI, 0.41-0.73) with no heterogeneity (chi2 of heterogeneity, 2.96; P = 0.4). In studies wherein only coronary artery bypass grafting was performed, statin treatment decreased postoperative atrial fibrillation (OR, 0.64; 95% CI, 0.43-0.95). We conclude that statin administration results in a reduction in the incidence of atrial fibrillation in patients who undergo cardiac surgery. Further research into the underlying mechanism can elucidate possible relationships between the dosage and type of statin used.

Journal article

James DRC, Orihuela-Espina F, Leff DR, Mylonas GP, Kwok K-W, Darzi AW, Yang G-Zet al., 2010, Cognitive Burden Estimation for Visuomotor Learning with fNIRS, 13th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Publisher: SPRINGER-VERLAG BERLIN, Pages: 319-326, ISSN: 0302-9743

Conference paper

Paggetti G, Menegaz G, Leff DR, Orihuela-Espina F, Darzi A, Yang G-Zet al., 2010, Exploring the link between depth perception, hand eye coordination and parietal lobe activation during robotic-assisted interventions, PERCEPTION, Vol: 39, Pages: 162-163, ISSN: 0301-0066

Journal article

Paggetti G, Lin Y-C, Menegaz G, Leff DR, Yang G-Zet al., 2010, DOES IT EXIST A LINK BETWEEN PERFORMANCE AND PARIETAL CORTEX ACTIVITY IN SURGICAL TASKS?, International Conference on Fuzzy Computation (ICFC 2010) and International Conference on Neural Computation (ICNC 2010), Publisher: SCITEPRESS, Pages: 381-384

Conference paper

Saso S, Vecht JA, Rao C, Protopapas A, Ashrafian H, Leff D, Darzi A, Athanasiou Tet al., 2009, Statin Therapy May Influence the Incidence of Postoperative Atrial Fibrillation What Is the Evidence?, TEXAS HEART INSTITUTE JOURNAL, Vol: 36, Pages: 521-529, ISSN: 0730-2347

Journal article

Leff DR, Heath D, 2009, Surgery for obesity in adulthood., BMJ, Vol: 339

Journal article

Leff DR, Hassell J, Sufi P, Heath Det al., 2009, Emergency and elective laparoscopic repair of spigelian hernias: two case reports and a review of the literature, Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, Vol: 19, Pages: e152-e155, ISSN: 1530-4515

Diagnosing spigelian hernias through physical examinationcan be particularly challenging. Increasingly, laparoscopy isbeing used to both confirm the diagnosis and carry out therapeuticrepair. Here, we describe 2 cases of successful laparoscopic repairof spigelian hernias using an Endocatch assisted sutured technique.A review of the literature describing the role of laparoscopy in themanagement of spigelian hernia is also provided.

Journal article

Patten DK, Layfield D, Arya S, Leff DR, Paraskevas PAet al., 2009, Single Best Answers in Surgery (SBA), Publisher: Hodder and Arnold, ISBN: 978-0340972359

Single Best Answers in Surgery offers a new approach to revising for surgical finals; by not only indicating the correct answer to each question, but explaining the full rationale used for finding the answer in each case. This means the book is invaluable not only for self-testing before an exam, but will have long-term value throughout a student's surgical studies, through to finals exams and beyond. The questions are arranged into topic areas, followed by a practice exam for true self-assessment.

Book

Warren OJ, Leff DR, Athanasiou T, Kennard C, Darzi Aet al., 2009, The Neurocognitive Enhancement of Surgeons: An Ethical Perspective, JOURNAL OF SURGICAL RESEARCH, Vol: 152, Pages: 167-172, ISSN: 0022-4804

Journal article

Leff DR, Orihuela-Espina F, Atallah L, Athanasiou T, Leong JJH, Darzi AW, Yang G-Zet al., 2008, Functional prefrontal reorganization accompanies learning-associated refinements in surgery: A manifold embedding approach, 10th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI 2007), Publisher: TAYLOR & FRANCIS LTD, Pages: 325-339, ISSN: 1092-9088

Conference paper

Leff DR, Orihuela-Espina F, Atallah L, Athanasiou T, Leong JJH, Darzi AW, Yang G-Zet al., 2008, Functional prefrontal reorganization accompanies learning-associated refinements in surgery: a manifold embedding approach., Comput Aided Surg, Vol: 13, Pages: 325-339

The prefrontal cortex (PFC) is known to be vital for acquisition of visuomotor skills, but its role in the attainment of complex technical skills which comprise both perceptual and motor components, such as those associated with surgery, remains poorly understood. We hypothesized that the prefrontal response to a surgical knot-tying task would be highly dependent on technical expertise, and that activation would wane in the context of learning success following extended practice. The present series of experiments investigated this issue, using functional Near Infrared Spectroscopy (fNIRS) and dexterity analysis to compare the PFC responses and technical skill of expert and novice surgeons performing a surgical knot-tying task in a block design experiment. Applying a data-embedding technique known as Isomap and Earth Mover's Distance (EMD) analysis, marked differences in cortical hemodynamic responses between expert and novice surgeons have been found. To determine whether refinement in technical skill was associated with reduced PFC demands, a second experiment assessed the impact of pre- and post-training on the PFC responses in novices. Significant improvements (p < 0.01) were observed in all performance parameters following training. Smaller EMD distances were observed between expert surgeons and novices following training, suggesting an evolving pattern of cortical responses. A random effect model demonstrated a statistically significant decrease in relative changes of total hemoglobin (Delta HbT) [coefficient = -3.825, standard error (s.e.) = 0.8353, z = -4.58, p < 0.001] and oxygenated hemoglobin (Delta HbO(2)) [coefficient = -4.6815, s.e = 0.6781, z = -6.90, p < 0.001] and a significant increase in deoxygenated hemoglobin (Delta HHb) [coefficient = 0.8192, s.e = 0.3034, z = 2.66, p < 0.01] across training. The results indicate that learning-related refinements in technical performance are mediated by temporal reductions in prefrontal activation.

Journal article

Leff D, Leong J, Orihuela-Espina F, Atallah L, Elwell C, Delpy D, Yang GZ, Darzi Aet al., 2008, Variations in prefrontal activation support technical performance improvements in surgical novices, Annual Meeting of the Society-of-Academic-and-Research-Surgery, Publisher: WILEY-BLACKWELL, Pages: 936-936, ISSN: 0007-1323

Conference paper

Leong JJH, Leff DR, Das A, Aggarwal R, Reilly P, Atkinson HDE, Emery RJ, Darzi AWet al., 2008, Validation of orthopaedic bench models for trauma surgery., J Bone Joint Surg Br, Vol: 90, Pages: 958-965

The aim of this study was to validate the use of three models of fracture fixation in the assessment of technical skills. We recruited 21 subjects (six experts, seven intermediates, and eight novices) to perform three procedures: application of a dynamic compression plate on a cadaver porcine model, insertion of an unreamed tibial intramedullary nail, and application of a forearm external fixator, both on synthetic bone models. The primary outcome measures were the Objective Structural Assessment of technical skills global rating scale on video recordings of the procedures which were scored by two independent expert observers, and the hand movements of the surgeons which were analysed using the Imperial College Surgical Assessment Device. The video scores were significantly different for the three groups in all three procedures (p < 0.05), with excellent inter-rater reliability (alpha = 0.88). The novice and intermediate groups specifically were significantly different in their performance with dynamic compression plate and intramedullary nails (p < 0.05). Movement analysis distinguished between the three groups in the dynamic compression plate model, but a ceiling effect was demonstrated in the intramedullary nail and external fixator procedures, where intermediates and experts performed to comparable standards (p > 0.6). A total of 85% (18 of 21) of the subjects found the dynamic compression model and 57% (12 of 21) found all the models acceptable tools of assessment. This study has validated a low-cost, high-fidelity porcine dynamic compression plate model using video rating scores for skills assessment and movement analysis. It has also demonstrated that Synbone models for the application of and intramedullary nail and an external fixator are less sensitive and should be improved for further assessment of surgical skills in trauma. The availability of valid objective tools of assessment of surgical skills allows further studies into improving methods of

Journal article

Leff DR, Leong JJH, Warren O, Athanasiou T, Yang G-Z, Darzi Aet al., 2008, Near-infrared spectroscopy: Potential clinical benefits in surgery, JOURNAL OF THE AMERICAN COLLEGE OF SURGEONS, Vol: 206, Pages: 761-762, ISSN: 1072-7515

Journal article

Leff DR, Aggarwal R, Rana M, Nakhjavani B, Purkayastha S, Khullar V, Darzi AWet al., 2008, Laparoscopic skills suffer on the first shift of sequential night shifts: Program directors beware and residents prepare, ANNALS OF SURGERY, Vol: 247, Pages: 530-539, ISSN: 0003-4932

Journal article

Leff DR, Leong JJH, Aggarwal R, Yang G-Z, Darzi Aet al., 2008, Could variations-in technical skills acquisition in surgery be explained by differences in cortical plasticity?, ANNALS OF SURGERY, Vol: 247, Pages: 540-543, ISSN: 0003-4932

Journal article

Leff DR, Warren OJ, Enfield LC, Gibson A, Athanasiou T, Patten DK, Hebden J, Yang GZ, Darzi Aet al., 2008, Diffuse optical imaging of the healthy and diseased breast: A systematic review, BREAST CANCER RESEARCH AND TREATMENT, Vol: 108, Pages: 9-22, ISSN: 0167-6806

Journal article

Aggarwal R, Leong J, Leff D, Warren O, Yang G-Z, Darzi Aet al., 2008, New technologies for the surgical curriculum, WORLD JOURNAL OF SURGERY, Vol: 32, Pages: 213-216, ISSN: 0364-2313

Journal article

Warren OJ, Alcock EMH, Choong AMTL, Leff DR, Van Herzeele I, Darzi AW, Athanasiou T, Cheshire NJWet al., 2008, Recombinant activated factor VII: A solution to refractory haemorrhage in vascular surgery?, EUROPEAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY, Vol: 35, Pages: 145-152, ISSN: 1078-5884

Journal article

Leff DR, Elwell CE, Orihuela-Espina F, Atallah L, Delpy DT, Darzi AW, Yang GZet al., 2008, Changes in prefrontal cortical behaviour depend upon familiarity on a bimanual co-ordination task: An fNIRS study, NEUROIMAGE, Vol: 39, Pages: 805-813, ISSN: 1053-8119

Journal article

Leff DR, Orihuela-Espina F, Leong J, Darzi A, Yang G-Zet al., 2008, Modelling Dynamic Fronto-Parietal Behaviour During Minimally Invasive Surgery - A Markovian Trip Distribution Approach, 11th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI2008), Publisher: SPRINGER-VERLAG BERLIN, Pages: 595-602, ISSN: 0302-9743

Conference paper

Leff DR, Leong J, Yang G-Z, Darzi AWet al., 2008, Visuo-spatial ability and fMRI cortical activation insurgery residents, AMERICAN JOURNAL OF SURGERY, Vol: 195, Pages: 138-138, ISSN: 0002-9610

Journal article

Leong JJH, Atallah L, Mylonas GP, Leff DR, Emery RJ, Darzi AW, Yang G-Zet al., 2008, Investigation of partial directed coherence for hand-eye coordination in laparoscopic training, 4th International Workshop on Medical Imaging and Augmented Reality, Publisher: SPRINGER-VERLAG BERLIN, Pages: 270-+, ISSN: 0302-9743

Conference paper

Leff D, Aziz O, Darzi A, 2007, Trucks, planes, and scalpels - Is there an evidence-based approach to surgeons' working hours?, ARCHIVES OF SURGERY, Vol: 142, Pages: 817-820, ISSN: 0004-0010

Journal article

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