Mean Shortest Distance Research Articles

Morphology of the lateral circumflex femoral artery in adult cadavers.

The lateral circumflex femoral artery (LCFA) is important for surgical approaches to the hip joint; its branches are often used as grafts and pedicled flaps. Our aim was to contribute to the literature by reporting variations. The LCFA branching pattern was studied in 26 lower limbs of formalin-fixed cadavers. It was recorded whether the LCFA originated from the femoral artery (FA) or the deep femoral artery (DFA). The distances of LCFA from the mid-inguinal point (MIP) and DFA; and the diameters of LCFA and its branches were measured with metric caliper. Side differences were analyzed by Wilcoxon test. The mean shortest distance from the LCFA to the MIP was 59.45 ± 13.06mm and to the DFA was 19.23 ± 9.63mm. The mean diameters of LCFA and its ascending, transverse, and descending branches were 5.82 ± 1.87mm, 3.28 ± 0.87mm, 3.02 ± 0.92mm, and 3.61 ± 0.98mm, respectively. The LCFA originated from 80.8% DFA and 19.2% FA. Data were evaluated jointly (p > 0.05). In one case, an accessory transverse branch was found. Spearman analysis shows that as the distance between the LCFA and the MIP increased, the diameter of the LCFA and its branches increased. Knowledge of the LCFA branching pattern is essential for interventional options in arterial grafts, such as bypass surgery, pedicled flaps, and surgical approaches to the hip joint. Preoperative radiologic evaluation for accurate knowledge of the topography of the branching pattern and vessel size can contribute to successful management of intraoperative blood loss and avoidance of iatrogenic injury.

Movement of the superior mesenteric artery in patients with superior mesenteric artery syndrome: A case-reference study.

Superior mesenteric artery (SMA) syndrome is related to the reduction of the aortomesenteric angle on detailed imaging studies; i.e., an expert's ultrasonography or angiography. We aimed to test a simpler imaging finding of SMA syndrome. This cross-sectional case-reference study examined whether right movement of the SMA on unenhanced computed tomography (CT) is useful for the diagnosis of SMA syndrome. We reviewed hospital records of patients admitted in 2008-2018. Each case was matched to one non-case patient of the same age and sex. On unenhanced CT scans, we identified the shortest distance between the parallel line that passes through the center of the aorta to the line that bisects the spine and SMA. A negative number of the distance means that the SMA is on the left side of the above-described parallel line. There was a total of 14 cases and 14 non-cases (men, 57.1%) with mean age 78.7 years. Mean body mass index of cases and non-cases were 19.2 and 22.2kg/m2 , respectively. The more prevalent side of the SMA was the right side. The mean shortest distance was 10.5 mm in cases and 0.7 mm in non-cases (p for independent t test=0.043). For comparing the observations in SMA cases at several time points, the mean shortest distance at pre-onset was -2.7 mm, with a significant difference from that at onset (p for paired t test=0.030). In conclusion, right movement of the SMA diagnosed by unenhanced CT is associated with SMA syndrome.

Interocular asymmetry in distribution of leaks in central serous chorioretinopathy.

To study interocular asymmetry in distribution of leaks in central serous chorioretinopathy (CSC). Patients with unilateral CSC were included in this retrospective multicenter study. All patients received multimodal imaging. The prevalence of leaks within 1 disk diameter (DD) peripapillary area and the mean shortest distance between a leak and the optic disk edge was analyzed for the right and left eyes separately based on FA images. Clinical and morphological characteristics were collected and compared between eyes with a peripapillary leak and eyes with a leak elsewhere. In total, 152 eyes (77 right eyes and 75 left eyes) of 152 patients (128 males and 24 females) with a mean age of 45.2 ± 9.8years were included. The mean distance from the leak to the edge of the optic disk was statistically significantly lower (p = 0.0003), and the prevalence of the leaks within the 1 DD-peripapillary area was higher in the left eye than in the right eye (32.1% versus 10.7%, respectively, p = 0.0017). The eyes with a peripapillary leak had a longer duration of the disease (p < 0.05), a wider area of retinal pigment epithelium alteration (p < 0.001), and a higher prevalence of outer retinal atrophy (p < 0.001) compared to the eyes with a leak elsewhere. The left eye showed closer location of the leak to the optic disk edge and higher prevalence of leaks within the peripapillary area. The cases with peripapillary leak commonly demonstrated characteristics of chronic CSC despite relative preservation of visual acuity.

An anatomical neurovascular study for procedures targeting peri-articular nerves in patients with anterior knee pain

BackgroundRadiofrequency ablation (RFA) of the articular branches innervating the anterior knee capsule has been studied as a possible alternative to surgery for degenerative arthritis. However, the neurovascular topography of the anterior knee capsule remains unclear. MethodsOne leg from each of the 20 formalin-embalmed cadaveric specimens was investigated. Modified ablation points (MAPs) were evaluated for a possible alternative for conventional target points (CAPs). ResultsFor the nerve to vastus medialis (NVM), the probability of identifying the nerve was higher at MAP compared with CAP (62.5% vs. 25%). The mean shortest distance from the nerve was shorter at MAP compared with CAP (18.0 mm vs. 29.9 mm). The probabilities and distances for other nerves were not significantly different between the points. However, the probability of identifying the artery was significantly lower at MAPs compared with CAPs for arteries (0%, 5.3%, and 0% vs. 84.2%, 84.2%, and 73.3% for superior medial genicular, superior lateral genicular, and inferior medial genicular artery, respectively). For the recurrent peroneal nerve (RPN), a new target point was set in MAPs. ConclusionsThe current landmark for genicular nerve procedures may not accurately target the correct nerve position, or reduce the risk for vessel damage. A more proximal target may reduce complications and increase the probability of successful procedures, although clinical correlation is needed.

Proximity of the maxillary artery to the mandibular ramus: An anatomic study using three‐dimensional reconstruction of computer tomography

The maxillary artery (MA) is the main source of brisk bleeding during maxillectomy and procedures in the subcondylar portion of the mandible. The purpose of the study was to investigate the relationship between the MA and the mandible in the infratemporal fossa. The CT scans of 100 patients were retrospectively evaluated. The distances from the MA to bony landmarks were assessed in a three-dimensional model of the CT scan. In the cases where the MA was lateral to the LP [164 of 200 MAs (82%)], the mean shortest distances from the MA to the apex of the coronoid and condyle and the deepest portion of the mandibular notch were 13.6 ± 1.6 mm, 21.3 ± 2.0 mm, and 3.6 ± 1.0 mm, respectively. The contact point between the MA and medial surface of the mandible was measured and found to be 3.6 ± 2.2 mm posterior and 1.7 ± 1.4 mm inferior relative to the deepest portion of the mandibular notch. In the cases where the MA was medial to the LP [36 of 200 MAs (18%)], the mean shortest distances from the MA to the apex of the coronoid and condyle and the deepest portion of the mandibular notch were 19.5 ± 2.5 mm, 20.7 ± 2.4 mm, and 16.3 ± 3.7 mm, respectively. The studied measurements will help guide surgeons to determine the anatomy of the operative field in relation to the MA and minimize risks of injuring the vessel.

Three-dimensional reconstruction of the femoral footprint of anterior cruciate ligment by dual-source CT

Objective To reconstruct three-dimensional femoral footprint of the anterior cruciate ligament (ACL) by dual-source CT (DSCT),which can provide a novel positioning system particularly applicable in the anatomic ACL reconstruction under arthroscopy. Methods DSCT scanning was performed for the bilateral knees of 30 healthy volunteers.Three-dimensional reconstruction of the lateral wall of the intercondylar notch was done with 64-slice spiral CT workstation (GE,Volume Share2-AW 4.4 version).Double-bundle footprints of the ACL femoral insertions were identified, outlined and marked on the three-dimensional models.The over-the-top junction of the distal femur and the trochlea of femoral lateral condyle was dotted as a reference point O.The femoral footprint long and short axes,the footprint angle between the line passing through 2 centers of anteromedial and posterolateral bundles and the femoral shaft,the distance between 2 bundle centers,the shortest distance from the footprint edge to the distal femoral cartilage,and the shortest distance from the footprint edge to the posterior margin of the femoral cartilage were measured on the models with a standardized scale. Results All the ACL femoral footprints were successfully reconstructed by DSCT in the 60 knee joints.They were relatively protruding,plain,irregular in shape but identical in grey scale,distinct areas on the image. On the three-dimensional models of femoral lateral condyle,a 3-point-2-angle positioning system applicable in arthroscopic anatomic ACL reconstruction was successfully established and used to define and describe the double-bundle insertions of ACL.The mean long and short axes of ACL femoral footprint were respectively 16.5 ± 1.8 mm and 8.0 ± 1.3 mm; the mean ACL footprint angle was 8.3° ±4.9°; the mean distance between 2 bundle centers was 7.8 ± 1.0 mm; the mean shortest distance from the footprint edge to the distal femoral cartilage was 1.6 ± 1.5 mm; the mean shortest distance from the footprint edge to the posterior margin of the femoral cartilage was 1.7 ± 0.9 mm. Conclusions Three-dimensional ACL femoral footprints can be clearly reconstructed with DSCT.Natural ACL femoral footprints vary from person to person,which indicates a need of individualized reconstruction in order to restore the anatomy in maximum.The 3-point-2-angle positioning system we have developed is just suitable for arthroscopic ACL reconstruction. Key words: Anterior cruciate ligament; Femur; Tomography, spiral computed

High-Grade Glioma Relationship to the Neural Stem Cell Compartment: A Retrospective Review of 104 Cases

To assess the incidence of involvement of the neural stem cell (NSC) compartment by high-grade astrocytomas in a series of adult patients. One hundred four initial diagnostic cranial magnetic resonance imaging series were reviewed. For each series, the gross tumor volume (GTV; enhancing tumor on T(1)), edema (hyperintensity on T(2) FLAIR), and the NSC compartment (hippocampal formation and lateral ventricle plus a 5-mm expansion) were identified. Involvement of NSC by GTV and edema was assessed. For tumors not involving NSC, we measured distances from NSC to GTV and edema. Maximum diameters of GTV were measured for each case. Subset analysis was performed for GTV of ≤ 2 cm and ≤ 3 cm in maximum diameter to assess the incidence of involvement of NSC by this group of smaller tumors. For 10 representative tumors, minimum distances from GTV center to NSC were calculated. A total of 103/104 (99.0%) tumors, regardless of GTV maximum diameter, demonstrated involvement of NSC. A total of 101/104 (97.1%) tumors had NSC involvement by GTV, and 2/104 (1.9%) patients showed edema only. For GTV not involving NSC, the mean distance from NSC to GTV was 0.8 cm (range, 0.5--1.4 cm). The mean shortest distance from the center of GTV to NSC was 1.5 cm (range, 0.9--2.6 cm). Involvement of NSC by GTV was 90.9% (10/11 tumors) for GTV of ≤ 2 cm and 95.7% (22/23 tumors) for GTV of ≤ 3 cm. Our results support the hypothesis that the NSC compartment represents the putative site of origin for these tumors. NSC involvement does not appear to represent a volumetric phenomenon.

SU-GG-BRC-03: Real Time 3D Tracking of the HDR Source Using Flat Panel Detector

Purpose: This is a proof of concept study with the objective of reconstructing the position of an HDR source in 3D in real‐time using a flat panel detector(FPD). It can potentially become the new standard in Quality Assurance (QA) for treatment delivery. Method and Materials: A matrix of markers (Ball Bearings 4mm in diameter) with precisely known locations was mounted on the cover of a flat panel detector(Acuity, Varian Inc) at variable height. Images acquired with the x‐ray source were used to calibrate the system. A plan with three dwell positions, well defined in 3D was created and delivered. Images were acquired with the FPD during the delivery of ‘treatment’. In house software was created to automatically segment and label the markers' images. A mathematical solution for the ‘near‐intersection’ of two 3D lines was implemented and used to determine the ‘true’ 3D source position. Each line was defined by the 3D positions of each marker and its projection on the FPD. A matrix with N markers will produce N*(N‐1)/2 points of intersection and their mean will result in a more accurate source position. The HDR source was placed on a 5cm solid water to mimic the patient and the FPD was placed at distances varying from 50 to 70cm. Results: The best imaging geometry was determined and images of markers obtained with the HDR source (strength of 6.2Ci) were properly segmented at all distances. During delivery, the source was located at [0,0,50], [0.5,0,50] and [2.0, 0, 50]. The reconstructed positions were [0,0,50.130], [0.497,−0.008,50.106] and [1.984, −0.005,50.053] with a standard deviation of [0.027,0.019,0.115]cm. When intersecting lines in 3D, the mean shortest distance between any two lines was 0.025cm with standard deviation 0.016cm. Conclusion: We proved that the accuracy of source position detection in 3D using a FPD is sub‐millimeter.

A new method to normalize plantar pressure measurements for foot size and foot progression angle

Plantar pressure measurement provides important information about the structure and function of the foot and is a helpful tool to evaluate patients with foot complaints. In general, average and maximum plantar pressure of 6–11 areas under the foot are used to compare groups of subjects. However, masking the foot means a loss of important information about the plantar pressure distribution pattern. Therefore, the purpose of this study was to develop and test a simple method that normalizes the plantar pressure pattern for foot size, foot progression angle, and total plantar pressure. Moreover, scaling the plantar pressure to a standard foot opens the door for more sophisticated analysis techniques such as pattern recognition and machine learning. Twelve subjects walked at preferred and half of the preferred walking speed over a pressure plate. To test the method, subjects walked in a straight line and in an approaching angle of approximately 40°. To calculate the normalized foot, the plantar pressure pattern was rotated over the foot progression angle and normalized for foot size. After normalization, the mean shortest distance between the contour lines of straight walking and walking at an angle had a mean of 0.22 cm (SD: 0.06 cm) for the forefoot and 0.14 cm (SD: 0.06 cm) for the heel. In addition, the contour lines of normalized feet for the various subjects were almost identical. The proposed method appeared to be successful in aligning plantar pressure of various feet without losing information.

Spatial distribution, fruit production and seed removal of a rare, dioecious canopy tree species (Aglaia aff. flavida Merr. et Perr.) in Papua New Guinea

ABSTRACTAll mature individuals of Aglaia aff. flavida (Meliaceae) were mapped in a 260 ha study area at the Crater Mountain Biological Research Station in Papua New Guinea. Sixty-four reproductively mature trees were found in an aggregated distribution with a mean inter-tree distance of 88.9 m. The sample consisted of 35 female and 29 male trees with a mean shortest distance between sexes of 232 m. Seed production and seed removal of 22 female trees was monitored throughout the 1992 fruiting season. Female trees with in 200 m of male trees generally produced large seeds crops (&gt; 100 seeds) whereas trees farther than 200 m from the nearest male had small seed crops (&lt; 100 seeds) regardless of female size (DBH). Most seeds (63.2%, n = 3312) produced in a sub-sample of 22 trees came from the five most fecund trees, which also produced 74.1% of the seeds that were removed by vertebrate dispersers. Where a minority of a population of rare tropical trees produce the majority of progeny, sustainable harvest practices would be most effective where highly fecund individuals are identified and conserved.

992-111 Minimum Interelectrode Distance to Avoid Interactions Between Coexistent Transvenous Pacemaker and Defibrillator Systems

The coexistence of a dual-chamber (or ventricular) permanent pacemaker (PM) and a non-thoracotomy (NT) ICD may result in ICD nondetection of ventricular fibrillation during uninhibited ventricular pacing. This is important in light of the frequent concomitant use of both devices. Guidelines to avoid this interaction, specifically the minimum safe distance between the 2 electrodes, have not been established. In 33 pts with coexistent PM and NT-lCD, we measured the shortest distance from the PM electrodes to the ICD sensing electrodes using a tridimensional coordinate system on PA and lateral chest radiographs. Pts were extensively tested post-implant for potential deleterious device-to-device interaction. In 5 pts (15%), the ICD was inappropriately inhibited by asynchronous ventricular pacing during ventricular fibrillation. In this “Interaction Group”, the mean shortest distance from the PM electrodes to the ICD sensing electrodes was significantly shorter than in the “Non-Interaction Group” (1.6 cm vs. 3.4 cm. p = 0.03, Mann-Whitney test). Four out of 10 (40%) systems with shortest interelectrode distance &lt; 2.0 cm demonstrated interaction, while this occurred in only 1 of 23 (4%) systems with shortest interelectrode distance ≥ 2.0 cm (p = 0.02, Fisher's Exact test). 1. A distance of at least 2.0 cm between the PM electrodes and the ICD sensing electrodes will avoid deleterious interactions in the vast majority of pts. 2. The use of at least one active-fixation lead will facilitate achievement of this target interelectrode distance by allowing stable lead positioning in the RV outflow tract or septum. 3. Careful lead positioning does not obviate the need for intra- and postoperative testing to identify potentially life-threatening device-to-device interaction.

Skull radiograph measurements of normals and patients with basilar impression; use of Landzert's angle.

One hundred normal lateral skull radiographs were studied and those of ten patients with basilar impression attending Kenyatta Hospital, Nairobi. The mean shortest distance of the odontoid tip to McGregor's basal line was 1.2 +/- 2.28 mm below the basal line (range 6 mm below to 3 mm above basal line), in normals and 9 +/- 2.7 mm (6-14 mm) above basal line in patients. The mean basal angle was 113 degrees +/- 7 degrees (102 degrees-133 degrees) in normals and 122 degrees +/- 6 degrees (113 degrees-125 degrees) in patients. The mean nasion-basion-opisthion angle was 162 degrees +/- 4 degrees (154 degrees-169 degrees) in normals and 178 degrees +/- 5 degrees (173 degrees-185 degrees) in patients. The mean total length of clivus was 48 +/- 3.7 mm (43-56 mm) in normals and 44 +/- 6.6 (36-48 mm) in patients group. The mean median diameter of the foramen magnum was 39 +/- 5 mm (30-48 mm), atlas 21 +/- 3 mm (18-25 mm) axis 18 +/- 3 mm (14-23 mm), third cervical vertebra 16 +/- 2 mm (13-22 mm) in normals and in patients: 39 +/- 4 mm (36-45 mm), atlas 23 +/- 6 (15-30 mm) axis 19 +/- 4 mm (16-25 mm), third cervical vertebra 16 +/- 3 (14-20). There was a significant difference in the position of the odontoid tip and the nasion-basion-opisthion angle between the normal and patient groups. All the other parameters measured in this work did not differ significantly between the two groups.