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Objectives: Stroke or cerebrovascular accident is associated with defects in the circle of Willis; the vascular network that supplies the brain. There is currently lack of literature on the involvement of the circle of Willis in patients with stroke or its association with impending stroke. The objective of the study was to evaluate luminal diameter of arteries that constitute the circle of Willis in patients with stroke using computed tomography angiography (CTA) and magnetic resonance imaging (MRI) scans. Material and Methods: Angiograms of 340 male and female patients aged 15–>75 (40.18 ± 1.1 and 43.68 ± 1.18) years with suspected stroke, referred for either brain CTA or MRI in selected hospitals/diagnostic centers in Nigeria were evaluated using RadiAnt and the MicroDicom viewer software applications. A retrospective descriptive research design was adopted with approval from the federal health research ethics committee. Direct measurement of luminal diameter of major arteries of the circle of Willis was done using SPSS version 25 at P < 0.05. Results: From the 340 images assessed, 256 (75.29%) patients had ischemic stroke with luminal diameter of arteries of the circle of Willis ranged from 1 mm to >3 mm while 84 (24.71%) patients were without stroke with luminal diameter ranged from 1 mm to 2.11 mm (P < 0.05). Conclusion: Patients with stroke have larger luminal diameter of arteries that form the circle of Willis when compared to patients without stroke. The study has established for the 1st time, luminal diameter of circle of Willis that may be an index in the sampled Nigerian population.

We attempted to improve the accuracy of coronary CT angiography (CCTA)-derived fractional flow reserve (FFR) (FFRCT) by expanding the coronary tree in the computational fluid dynamics (CFD) domain. An observational study was performed to evaluate the effects of extending the coronary tree analysis for FFRCT from a minimal diameter of 1.2 to 0.8 mm. Patients who underwent CCTA and interventional FFR were enrolled retrospectively. Seventy-six patients qualified based on the inclusion criteria. The three-dimensional (3D) coronary artery tree was reconstructed to generate a finite element mesh for each subject with different lower limits of luminal diameter (1.2 mm and 0.8 mm). Outlet boundary conditions were defined according to Murray’s law. The Newton–Krylov–Schwarz (NKS) method was applied to solve the governing equations of CFD to derive FFRCT. At the individual patient level, extending the minimal diameter of the coronary tree from 1.2 to 0.8 mm improved the sensitivity of FFRCT by 16.7% (p = 0.022). This led to the conversion of four false-negative cases into true-positive cases. The AUC value of the ROC curve increased from 0.74 to 0.83. Moreover, the NKS method can solve the computational problem of extending the coronary tree to an 0.8-mm luminal diameter in 10.5 min with 2160 processor cores. Extending the reconstructed coronary tree to a smaller luminal diameter can considerably improve the sensitivity of FFRCT. The NKS method can achieve favorable computational times for future clinical applications. • Extending the reconstructed coronary tree to a smaller luminal diameter can considerably improve the sensitivity of FFR CT . • The NKS method applied in our study can effectively reduce the computational time of this process for future clinical applications.

Although the adverse events of pathologic Vieussens' arterial ring (VAR) have been reported, it is difficult to determine optimal clinical management. Thus, we hypothesized that the luminal diameter ratio of VAR obtained from coronary computed tomography angiography (CCTA) could be used as a clinical tool to inform appropriate patient management.A total of 29 patients with pathologic VAR were retrospectively recruited for this study. The VAR luminal diameter ratio was defined as a quotient of VAR fistula divided by the orifice of RCA or LAD, based on which, patients were divided into small fistula group and large fistula group. The AUC, sensitivity, specificity, positive and negative predictive values were obtained from ROC curve. The cutoff value of the VAR luminal diameter ratio was calculated and assessed during the follow-up.The VAR luminal diameter ratio of fistula/RCA orifice was 0.505 ± 0.098 in small fistula group and 1.020 ± 0.150 in large fistula group. The VAR luminal diameter ratio of fistula/LAD orifice was 0.507 ± 0.123 in small fistula group and 1.039 ± 0.151 in large group. The value was correlated with the choice of the treatment (r = 0.643 p 0.01, r = 0.627 p 0.01). The AUC, sensitivity, specificity, positive and negative predictive values were 0.803, 54.5%, 100%, 100% and 78.3% of the fistula/RCA orifice ratio and 0.833, 63.64%, 94.44%, 87.5% and 81.0% of the fistula/LAD orifice ratio, respectively. The cutoff values of both fistula/RCA orifice and fistula/LAD orifice ratios were 0.676.The VAR luminal diameter ratio may be a valuable index to determine appropriate treatment for patients with pathologic VAR.

Objective: The objective of the study was to develop a reference luminal diameter (LD) of the abdominal aorta (AA) in Abuja, Nigeria. Methods: The LD of the AA of 422 male and female healthy subjects was measured sonographically using standard protocol. The relationship between age, body mass index (BMI), gender, and the LD of the AA was determined in the subjects. Statistical analysis was performed by the Student’s t-test and Pearson’s correlation coefficient at p < 0.05 level of significance. Results: The values of the LD of the AA in the healthy subjects were 15.16 ± 0.55 mm in males and 15.15 ± 0.55 mm in females. The 5th and 95th percentile normal reference limits of the AA were 14.20–16.10 mm, respectively. There were no significant differences in the LD measurements in male and female subjects. Age correlated strongly positively with LD (ɼ=0.90) of the AA in both genders. BMI showed weak positive correlation with LD (ɼ=0.136) of the AA in female healthy subjects only. Conclusion: The reference LD of the AA in the study population was 15.16 ± 0.55 mm in males and 15.15 ± 0.55 mm in females. The LD of the AA increased proportionately with age.

This study evaluated the calcium blooming-reducing effect and the differences of luminal diameter among various-energy virtual monochromatic images (VMIs) using rapid kilovolt-switching dual-energy computed tomography (DECT). Forty-five calcified segments in 31 patients were analyzed. For the analysis, 40- to 140-keV VMIs on both non-contrast CT and coronary CT angiography were generated at 10-keV steps, and calcification size and luminal diameter were measured using CT number profile curve and full-width at half-maximum method. We compared calcification size and luminal diameter on each keV VMIs with those on 70-keV VMI. There was no significant differences among the 40- to 140-keV VMIs regarding calcification size or luminal diameter. The 40- to 140-keV VMIs produced by single-source DECT had no effect on the calcification size or luminal diameter in the coronary artery.

Background: Many researches and studies were performed to investigate many aspects of the vermiform appendix. Many variations were observed at the different regions, among that, the focus was made on the lymphoid number and diameter, wall thickness, and luminal diameter. Objective: The aim of this work was to a finding of histomorphometery features of the adult vermiform appendix for different sex and age groups. Materials & methods: Fifty cadavers were included and divided into five age groups; A(20-29), B(30-39), C(40-49), D(50-59), and E(60-70)years. Ten cadavers were included for each age group. The inclusion criteria of the cadavers were brain stroke, built injuries, sudden death, car accident, and angina pectorals. The exclusion was with gangrenous, grossly inflammation and perforated appendices cadavers. Total length was measured from the base to the tip, as well as the diameter using a digital vernier caliper. Histological slides were made using HE Number and diameter of lymphoid follicles. Male and females have shown clear differences with increasing age groups.

Background We sought to compare quantitative coronary CT angiography (CTA) assessment versus standard clinical reading to identify heart transplanted (HTX) patients with progressive coronary wall thickening. Methods 35 patients (23 males, age 58 [IQR: 50;61] years) underwent 256-slice coronary CTA at one year and two years after HTX to rule out cardiac allograft vasculopathy (CAV). In addition to the standard clinical read, we quantified total vessel wall volume in all coronaries up to 2-mm luminal diameter. Fixed threshold settings were used to assess calcified (>350 HU) and non-calcified vessel wall components with high- (131–350 HU), intermediate- (75–130 HU) and low-attenuation ( Results Total lumen volume did not change between baseline and follow-up studies (p = 0.59). Total vessel wall volume showed significant increase (464 [IQR: 338; 570] vs. 563 [IQR: 345; 717] mm3, p Conclusion Quantitative coronary wall assessment is feasible with coronary CTA in HTX patients. Coronary wall thickening within the first two years after HTX is mainly attributable to non-calcified lesion components and might be an early sign of CAV.

Here we describe the use of a VBX balloon expandable stent-graft (WL Gore, Flagstaff, AZ, USA) to treat a right brachiocephalic vein stenosis in a haemodialysis patient prior to ipsilateral upper limb arterio-venous (AV) fistula formation. Balloon expandable stent-grafts are unsuitable for treating peripheral fistula stenoses due to their susceptibility of being crushed. The right brachiocephalic vein is both relatively short in comparison to the left and is less susceptible to extrinsic compression and the use of such a device to treat stenosis here allows for very accurate placement and restoration of luminal diameter. The advantages and disadvantages of using these devices in haemodialysis access circuits are also discussed herein, in what we believe to be the first report of the application of a dedicated commercially available balloon expandable stent graft in a haemodialysis patient.

Introduction This cross-sectional study sought to survey the current practice of computed tomography prior to transcatheter aortic valve implantation (CT-TAVI) in the United Kingdom. Methods All members of the British Society of Cardiovascular Imaging (BSCI) were invited to complete a 27-item online CT-TAVI survey. Results 47 responses were received from 40 cardiac centres, 23 (58%) of which performed TAVI on-site (TAVI centres). Only 6 respondents (13%) performed high volume activity (>200 scans per year) compared with 13 (28%) performing moderate (100–200 scans per year) and 27 (59%) performing low (0–99 scans per year) volume activity. Acquisition protocols varied (41% retrospective, 12% prospective with wide padding, 47% prospective with narrow padding), as did the phase of reporting (45% systolic, 37% diastolic, 11% both, 6% unreported) and use of beta blockade (22%). Median dose length product (DLP) was 675 mGy.cm (interquartile range 477 - 954 mGy.cm). Compared with non-TAVI centres, TAVI centres were more likely to report minimum ilio-femoral luminal diameter (n=25, 96% versus n=7, 58%, p=0.003) and optimal tube angulation for intervention (n=12, 46% versus n=1, 8%, p=0.02). TAVI centres trended towards using lower contrast volume than non-TAVI centres (98±27 vs. 118±42 ml, p=0.06); radiation doses did not differ (766±502 vs 801±461mGy.cm, p=0.66). Conclusion This national survey formally describes current CT-TAVI practice in the United Kingdom. High volume activity was only present at 1 in 7 cardiac CT centres. There is wide variation in scan acquisition, scan reporting and radiation dose exposure.

AimsOptical coherence tomography (OCT)-guided external elastic lamina (EEL)-based stent sizing is safe and as effective as intravascular ultrasound in achieving post-procedural lumen dimensions. However, when compared with automated lumen diameter (LD) measurements, this approach is time-consuming. We aimed to compare vessel diameter measurements and stent diameter selection using either of these approaches and examined whether applying a correction factor to automated LD measurements could result in selecting similar stent diameters to the EEL-based approach.Methods and resultsWe retrospectively compared EEL-based measurements vs. automated LD in reference segments in 154 OCT acquisitions and derived a correction factor for stent sizing using the ratio of EEL to LD measurements. We then prospectively applied the correction factor in 119 OCT acquisitions. EEL could be adequately identified in 100 acquisitions (84%) at the distal reference to allow vessel diameter measurement. Vessel diameters were larger with EEL-based vs. LD measurements at both proximal (4.12 ± 0.74 vs. 3.14 ± 0.67 mm, P 0.25 mm in 63% and potentially hazardous stent oversizing in 41% of cases.ConclusionEEL-based stent downsizing led to selection of larger stent diameters vs. LD upsizing. While applying a correction factor to automated LD measurements resulted in similar mean diameters to EEL-based measurements, this approach cannot be used clinically due to frequent and potentially hazardous stent over-sizing.

To select animals of appropriate size for preclinical studies of cardiovascular devices, reference knowledge of the cardiovascularanatomy relative to body weight is crucial. We measured the luminal diameters of the arteries (carotid, femoral, and iliac arteries) that are the common access vessels for endovascular and vascular procedures in Yorkshire×Landrace swine. Measurements were performed by using both ultrasound and angiographic methods and were correlated with body weight. Results showed no statistically significant difference between the left and right vessels in the diameters of the carotid,femoral, and iliac arteries. The diameters of the measured arteries showed high correlation with animal weight in pigs thatweighed less than 70 kg.

Background:Giant coronary aneurysms are the most severe complications of Kawasaki disease. There are few reports of outcomes from China. Most previous studies were based only on absolute aneurysmal dimensions. The aim of the present study was to catalog the outcomes of Kawasaki disease with giant coronary aneurysms in southwest China based on absolute dimensions and the z-score adjusted for body surface area.Methods and results:All patients diagnosed with giant coronary aneurysms (z-score ≥ 10 or absolute dimension ≥ 8 mm) between December, 2002 and December, 2018 were included. We retrospectively analysed patient characteristics and clinical data from 38 patients with giant coronary aneurysms. Over a median follow-up period of 30.5 months (range from 1.7 months to 22.3 years), including patients in chronic phase who had been diagnosed prior to 2002, eight patients had myocardial infarction, including two deaths and one patient with coronary artery bypass grafting. The 1-, 2-, and 5-year event-free rates were 0.63, 0.63, and 0.53 for thrombosis, respectively, and 0.86, 0.81, and 0.81 for major adverse cardiac events, respectively. The 1-, 2-, and 5-year regression-free rates were 0.94, 0.85, and 0.67, respectively. A total of 73.7% of patients remained active.Conclusion:In the early stages of Kawasaki disease, patients with giant coronary aneurysms often experience major cardiovascular events; however, they are also likely to have normalisation of the coronary internal luminal diameter. With long-term anticoagulation, close cardiologic monitoring, and prompt thrombolytic therapy, most patients can achieve disease-free periods.

Low grade appendiceal mucinous neoplasm (LAMN) is the primary source of pseudomyxoma peritonei (PMP). PMP may develop after seemingly complete resection of primary tumor by appendectomy, which is unpredictable due to lack of reliable prognostic indicators. We retrospectively reviewed 154 surgically resected LAMNs to explore if any of the macroscopic and microscopic characteristics may be associated with increasing risk of PMP development. Our major findings include: (1) As compared to those without PMP, the cases that developed PMP were more frequent to have (a) smaller luminal diameter (1 cm) and thicker wall, separate mucin aggregations, and microscopic perforation/rupture, all suggestive of luminal mucin leakage; (b) microscopic acellular mucin presenting on serosal surface and not being confined to mucosa; and (c) neoplastic epithelium dissecting outward beyond mucosa, however, with similar frequency of neoplastic cells being present in muscularis propria. (2) Involvement of neoplastic cells or/and acellular mucin at surgical margin did not necessarily lead to tumor recurrence or subsequent PMP, and clear margin did not absolutely prevent PMP development. (3) Coexisting diverticulum, resulted from neoplastic or non-neoplastic mucosa being herniated through muscle-lacking vascular hiatus of appendiceal wall, was seen in a quarter of LAMN cases, regardless of PMP. The diverticular portion of tumor involvement was often the weakest point where rupture occurred. In conclusion, proper evaluation of surgical specimens with search for mucin and neoplastic cells on serosa and for microscopic perforation, which are of prognostic significance, should be emphasized.

Background: Growth of the intracranial arteries facilitates the rapid increase in cerebral growth in the first 2 decades of life. In the age of cerebral endovascular treatment, many questions arise in the pediatric cohort regarding the safety and efficacy of these therapeutic approaches. Small arterial diameter may influence treatment selection in the very young, but to date little normative data is available to define vascular growth in infants and children. Methods: Subjects in this single-institution, retrospective cohort study were identified by MRI brain imaging keyword query as “normal” with age 0-18 years old at the time of the study. Medical records were reviewed to capture weight, length, and head circumference and exclude cerebrovascular or connective tissue disease risk factors. MRI T2-weighted images were measured to calculate the head circumference and arterial diameter in axial and coronal planes. A growth curve was created from the head circumferences and intracranial artery diameters to compare luminal caliber to age, sex and recorded growth parameters. Results: 317 subjects (170 female, 147 male) are included in the analysis. Luminal diameter was observed to increase rapidly in all arterial segments over the first 3 years of life. Compared to weight and length, head circumference most closely correlated with arterial size. Head circumference growth is most rapid during the first 3 years, tracking closely with the rate of luminal growth. An example relationship between arterial diameter and head circumference is shown in Figure 1. Conclusions: This is the largest cohort of cerebral arterial luminal growth in childhood. We show that arterial diameter can be measured non-invasively on MRI brain and correlated to routinely measured growth parameters. A better understanding of normal arterial growth is essential to our treatment of cerebrovascular disease in children.

Objective To examine whether no anisodamine injection before CTE was feasible without impairing image quality and diagnostic performance. Materials The change of mural thickness and luminal diameter were compared between using and no using anisodamine. The diagnostic performance of small-bowel disease was analyzed and compared. Results No motion artifact was detected in two groups. There was no significant difference regarding the change of luminal diameter and mural thickness (all P > 0.05). The diagnostic accuracy of small-bowel disease was no significant difference (P = 0.63). Conclusion Lack of anisodamine injection before CTE did not impair image quality and diagnostic performance compared with CTEs performed with anisodamine injection.

Background: The tracheobronchial tree is a branched distribution system that carries air from the trachea down to the acini which are the gas exchange units of the lung. In the trachea air speed is high and the airway is particularly vulnerable to obstruction by foreign bodies and tumors. The study of the morphological variations of luminal diameter of the trachea is of profound clinical importance as it may help the clinicians for smooth conduction of some maneuvers like endotracheal intubation and bronchoscopic procedure. It also helps the surgeons to deal with resection and reconstruction of the trachea.Objective: The present study was carried out to establish a Bangladeshi standard regarding the luminal diameter of the trachea and to minimize the dependency on foreign standards.Materials and Methods: This cross sectional descriptive study was performed on 70 post mortem human trachea (44 male and 26 female) to find out the difference in luminal diameter of the trachea of Bangledeshi people in relation to age and sex. The specimens were collected from the morgue in the department of Forensic Medicine, Mymensingh Medical College, Mymensingh by purposive sampling technique. All specimens were grouped into three groups according to age ? Group A, B and C. Dissection was performed according to standard autopsy techniques. The trachea was cut horizontally through the upper border of the 5th tracheal ring and the luminal diameter was measured. The average diameter was expressed in centimeter. All data were recorded in the predesigned data sheet and statistical analysis was done using computer based statistical package, SPSS to evaluate the significance of variance between the different findings.Results: In the present study the maximum luminal diameter of the trachea was 1.65 in Group A, 2.05 in Group B and 1.85 cm in Group C. The minimum luminal diameter of the trachea was 0.7 cm in Group A, 0.85 cm in Group B and in Group C 0.85 cm. The mean (±SD) luminal diameter of the trachea was 1.24 ± 0.3, 1.39 ± 0.3 and 1.29 ± 0.23 cm in Group A, B and C respectively. The maximum mean luminal diameter of the trachea was in Group B (1.39 cm) and minimum was in Group A (1.24 cm). The mean difference of luminal diameter of the trachea between groups was statistically non significant at p>0.5 level. The maximum mean (±SD) luminal diameter of the trachea was 1.50 ± 0.3 cm in male in Group B and minimum mean (±SD) luminal diameter of the trachea was 1.17 ± 0.26 cm in female in Group C. The mean luminal diameter of the male trachea was found to be greater than that of the female trachea among the age group. Mean difference between sexes in Group B was statistically highly significant at p

Small-bowel capsule endoscopy (CE) has recently been used in children. During the past few years, an intense research activity has defined the advantages and limitations of CE. Its uses have been established in several small-bowel pathologies such as obvious or obscure digestive bleeding, Crohn disease, and hereditary polyposis. Although the absence of biopsy reduces the specificity of CE findings, small-bowel exploration using CE achieves better accuracy in detecting lesions than most radiological examinations. In children, swallowing problems and the risk of retention due to stenosis are the main concerns when using CE: these problems can be solved using endoscopic delivery of the capsule and luminal diameter calibration, respectively. This review focuses on the evidence making CE indispensable to small-bowel exploration.

Purpose We compared the ability of intracranial high-resolution vessel wall imaging (VWI) without gadolinium and 3-D time-of-flight (3D-TOF) MRA techniques to characterize intracranial arterial stenosis and arterial wall plaque consistent with atherosclerotic plaque. Methods Consecutive intracranial VWI examinations performed within 2 months of a 3D-TOF exam with at least 1 noted plaque was included. Examinations assessed 17 vessel segments for plaque and diameters of stenotic and normal segments using double oblique reformatted images. Results were compared with the VWI and 3D-TOF exams considered the reference standard for plaque and luminal stenosis, respectively. Results Assessed segments totaled 286 from 17 patients. Proximal segment sensitivity and specificity for luminal stenosis detection with VWI was 92.5% and 82.1%, respectively, whereas for assessing plaque with 3D-TOF it was 59.4% and 98.3%, respectively. The mean intra-rater difference in luminal diameter measurements between VWI and 3D-TOF at normal segments and at the area of maximal stenosis was 0.02 mm (SD 0.51 mm) and 0.08 mm (SD 0.66 mm), respectively. Conclusions Intracranial VWI demonstrated reasonably high sensitivity and specificity for luminal stenosis assessment using 3D-TOF as a reference standard, while 3D-TOF demonstrated low sensitivity for plaque detection. Our results suggest that VWI can be used for simultaneous assessment of luminal stenosis and plaque in the intracranial arteries.

BACKGROUND AND PURPOSE: High-resolution MR imaging has recently been introduced as a promising diagnostic modality in intracranial artery disease. Our aim was to compare high-resolution MR imaging with digital subtraction angiography for the characterization and diagnosis of various intracranial artery diseases. MATERIALS AND METHODS: Thirty-seven patients who had undergone both high-resolution MR imaging and DSA for intracranial artery disease were enrolled in our study (August 2011 to April 2014). The time interval between the high-resolution MR imaging and DSA was within 1 month. The degree of stenosis and the minimal luminal diameter were independently measured by 2 observers in both DSA and high-resolution MR imaging, and the results were compared. Two observers independently diagnosed intracranial artery diseases on DSA and high-resolution MR imaging. The time interval between the diagnoses on DSA and high-resolution MR imaging was 2 weeks. Interobserver diagnostic agreement for each technique and intermodality diagnostic agreement for each observer were acquired. RESULTS: High-resolution MR imaging showed moderate-to-excellent agreement (interclass correlation coefficient = 0.892–0.949; κ = 0.548–0.614) and significant correlations ( R = 0.766–892) with DSA on the degree of stenosis and minimal luminal diameter. The interobserver diagnostic agreement was good for DSA (κ = 0.643) and excellent for high-resolution MR imaging (κ = 0.818). The intermodality diagnostic agreement was good (κ = 0.704) for observer 1 and moderate (κ = 0.579) for observer 2, respectively. CONCLUSIONS: High-resolution MR imaging may be an imaging method comparable with DSA for the characterization and diagnosis of various intracranial artery diseases.

ObjectiveThis cross-sectional observational study sought to describe variations in CT in the context of transcatheter aortic valve implantation (CT-TAVI) as currently performed in the UK.Methods408 members of the British Society of Cardiovascular Imaging were invited to complete a 27-item online CT-TAVI survey.Results47 responses (12% response rate) were received from 40 cardiac centres, 23 (58%) of which performed TAVI on-site (TAVI centres). Only six respondents (13%) performed high-volume activity (>200 scans per year) compared with 13 (28%) performing moderate (100–200 scans per year) and 27 (59%) performing low (0–99 scans per year) volume activity. Acquisition protocols varied (41% retrospective, 12% prospective with wide padding, 47% prospective with narrow padding), as did the phase of reporting (45% systolic, 37% diastolic, 11% both, 6% unreported). Median dose length product was 675 mGy.cm (IQR 477–954 mGy.cm). Compared with non-TAVI centres, TAVI centres were more likely to report minimum iliofemoral luminal diameter (n=25, 96% vs n=7, 58%, p=0.003) and optimal tube angulation for intervention (n=12, 46% vs n=1, 8%, p=0.02).ConclusionsThis national survey formally describes current CT-TAVI practice in the UK. High-volume activity was only present at one in seven cardiac CT centres. There is wide variation in scan acquisition, scan reporting and radiation dose exposure in cardiac CT centres.

Background The purpose of this study was to evaluate learning curves for an existing microsurgical training model. We compared efficiency and amount of training needed to achieve proficiency between novice microsurgeons without operative experience versus those who had completed a surgical internship. Methods Ten novice microsurgeons anastomosed a silastic tube model. Time to perform each anastomosis, luminal diameter, and number of errors were recorded. Results First year residents improved up to a brief plateau at 10 repetitions, followed by continued improvement. Second year residents improved up to a plateau at 10 repetitions with no further improvement thereafter. There was no significant difference in luminal area or errors between groups. Conclusion Residents with no operative experience can benefit from early exposure to microsurgical training. These interns continue to improve with additional repetitions while second year residents achieve proficiency with fewer repetitions.