Segmental and subsegmental arteries of the apical segment of the lower lobe of the left lung in man.
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Arteries↗
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Results for “Segmentation”
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Segment therapy. Textile segments in support of medication and physio-therapy.
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Clothing↗
[Corticofugal effects on interneuron segmental reactions of the ventral horn of the lumbar segments of the spinal cord in the cat].
Impulse activity of the lumbar ventral horn interneurons evoked by stimulation of afferent nerves of both hindlimbs is shown to be modulated (facilitated or inhibited) by descending volleys from the cerebral motor cortex. Facilitation was of short duration and did not exceed 35-40 ms. Duration of inhibition varied from 125 to 350 ms; in a few cases it lasted up to 500 ms. Polysynaptic reactions evoked in one and the same neuron by activation of different inputs were modulated differently: some of them could be depressed, while others--enhanced or unchanged. It is suggested that such differentiation is due to specific organization of these afferent inputs. Central latency of the test response was another main factor determining the type of its cortical modulation. Polysynaptic responses with a central delay less than 5 ms were facilitated or unchanged (in a few cases--depressed) while responses with central delay more than 5 ms were always depressed. Reactions with a latency more than 10 ms were depressed most deeply. Possible mechanisms and ways of transmission of corticofugal inhibition and facilitation are discussed.
Animals↗
Clinical uses of precordial ST-segment mapping and the pathophysiology of ST-segment voltage changes.
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Animals↗
[Individual difference of segmental structure of the lung in children and segmental resections].
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Age Factors↗
Patterns of colorectal liver metastases according to Couinaud's segments.
PURPOSE: It is commonly believed that the right lobe of the liver is the most frequent site of colorectal liver metastases. However, direct evidence for this is lacking in the literature. This study was designed to document and evaluate the pattern of liver metastases according to liver segments. METHODS: A retrospective medical records review of 270 patients with hepatic metastases from colorectal adenocarcinoma was performed to determine the pattern of metastases according to Couinaud's segments. There was operative confirmation of liver metastases in 202 patients (75 percent). A total of 1,166 segments were involved with liver metastases and were used in this analysis. Segment I was excluded from calculations because of its dual blood supply. When groups contained different numbers of Couinaud's segments an appropriate correction was made in the statistical comparison. RESULTS: There were 736 (63 percent) right lobe segments (V, VI, VII, VIII) and 430 (37 percent) left lobe segments (II, III, IV) involved with metastases (P < 0.001). Of 430 left lobe segments, 298 (69 percent) involved the left lateral segment (II, III) and 132 (31 percent) involved the medial segment (IV) of the left lobe (P = 0.25). When evaluating patients with 4 or less segments involved, there were 258 right lobe segments (75 percent) and 88 left lobe segments (25 percent) involved with metastases (P < 0.0001). Of 88 left lobe segments with 4 or less segments involved, there were 68 segments (77 percent) involving the left lateral segment and 20 segments (23 percent) involving the medial segment of the left lobe (P = 0.035). All of these relationships were statistically independent of the primary tumor site. CONCLUSIONS: We have documented an overall predominance of right hepatic lobe metastases independent of site of the primary colorectal carcinoma. However, when metastases occurred in the left lobe, the left lateral segment (II, III) was more commonly affected than the medial segment (IV), but this difference was statistically significant only when there were four or less segments involved with liver metastases.
Adenocarcinoma↗
A wrapper-based approach to image segmentation and classification.
The traditional processing flow of segmentation followed by classification in computer vision assumes that the segmentation is able to successfully extract the object of interest from the background image. It is extremely difficult to obtain a reliable segmentation without any prior knowledge about the object that is being extracted from the scene. This is further complicated by the lack of any clearly defined metrics for evaluating the quality of segmentation or for comparing segmentation algorithms. We propose a method of segmentation that addresses both of these issues, by using the object classification subsystem as an integral part of the segmentation. This will provide contextual information regarding the objects to be segmented, as well as allow us to use the probability of correct classification as a metric to determine the quality of the segmentation. We view traditional segmentation as a filter operating on the image that is independent of the classifier, much like the filter methods for feature selection. We propose a new paradigm for segmentation and classification that follows the wrapper methods of feature selection. Our method wraps the segmentation and classification together, and uses the classification accuracy as the metric to determine the best segmentation. By using shape as the classification feature, we are able to develop a segmentation algorithm that relaxes the requirement that the object of interest to be segmented must be homogeneous in some low-level image parameter, such as texture, color, or grayscale. This represents an improvement over other segmentation methods that have used classification information only to modify the segmenter parameters, since these algorithms still require an underlying homogeneity in some parameter space. Rather than considering our method as, yet, another segmentation algorithm, we propose that our wrapper method can be considered as an image segmentation framework, within which existing image segmentation algorithms may be executed. We show the performance of our proposed wrapper-based segmenter on real-world and complex images of automotive vehicle occupants for the purpose of recognizing infants on the passenger seat and disabling the vehicle airbag. This is an interesting application for testing the robustness of our approach, due to the complexity of the images, and, consequently, we believe the algorithm will be suitable for many other real-world applications.
Algorithms↗
Sequential motions of body segments in striking and throwing skills: descriptions and explanations.
The motions of segments participating in striking and throwing skills are generally sequenced in a proximal-to-distal fashion. These sequences are often described in terms of the linear velocities of the segment endpoints, joint angular velocities or segment angular velocities. While each method of description has its own merit, the latter is recommended since it leads to an intuitively pleasing way of explaining segment motions. Explanations of segment motion sequences are dependent not only on a knowledge of the joint moments driving the system of linked segments, but on the way the segments interact as functions of their motions and orientations. The motion-dependent interaction among segments is significant and offers an explanation of the sequencing of segment motions. As illustrated by the thigh and lower leg in kicking and by the upper arm and forearm in overarm pitching, the forward acceleration of the proximal segment plays a large role in causing the distal segment to lag behind. The subsequent forward acceleration of the distal segment is largely a result of the way the proximal segment interacts with the distal segment as a function of the proximal segment's angular velocity. The proximal segment is subsequently slowed down largely due to the motion-dependent effect of the distal segment on the proximal segment. Differences in the way segments interact in striking and throwing skills can account for variations in the timing of segment actions and these differences need to be examined before establishing general principles governing striking and throwing.
Biomechanical Phenomena↗
The protocadherin PAPC establishes segmental boundaries during somitogenesis in xenopus embryos.
BACKGROUND: One prominent example of segmentation in vertebrate embryos is the subdivision of the paraxial mesoderm into repeating, metameric structures called somites. During this process, cells in the presomitic mesoderm (PSM) are first patterned into segments leading secondarily to differences required for somite morphogenesis such as the formation of segmental boundaries. Recent studies have shown that a segmental pattern is generated in the PSM of Xenopus embryos by genes encoding a Mesp-like bHLH protein called Thylacine 1 and components of the Notch signaling pathway. These genes establish a repeating pattern of gene expression that subdivides cells in the PSM into anterior and posterior half segments, but how this pattern of gene expression leads to segmental boundaries is unknown. Recently, a member of the protocadherin family of cell adhesion molecules, called PAPC, has been shown to be expressed in the PSM of Xenopus embryos in a half segment pattern, suggesting that it could play a role in restricting cell mixing at the anterior segmental boundary. RESULTS: Here, we examine the expression and function of PAPC during segmentation of the paraxial mesoderm in Xenopus embryos. We show that Thylacine 1 and the Notch pathway establish segment identity one segment prior to the segmental expression of PAPC. Altering segmental identity in embryos by perturbing the activity of Thylacine 1 and the Notch pathway, or by treatment with a protein synthesis inhibitor, cycloheximide, leads to the predicted changes in the segmental expression of PAPC. By disrupting PAPC function in embryos using a putative dominant-negative or an activated form of PAPC, we show that segmental PAPC activity is required for proper somite formation as well as for maintaining segmental gene expression within the PSM. CONCLUSIONS: Segmental expression of PAPC is established in the PSM as a downstream consequence of segmental patterning by Thylacine 1 and the Notch pathway. We propose that PAPC is part of the mechanism that establishes the segmental boundaries between posterior and anterior cells in adjacent segments.
Animals↗
Segment interdependency and difficulty in two-stroke sequences.
We previously demonstrated that velocity and movement time for the initial segment for a two-stroke movement are scaled in relation to the difficulty of the second segment. The interdependent kinematic changes were interpreted as evidence that movement planning/organization processes consider the movement parameters of both segments when determining the movement characteristics of the entire sequence. In this experiment we examined two-stroke movements where the difficulty of the first segment had either a low or high level of difficulty to determine if the interdependent kinematic changes are diminished when parameter specification is high for the initial segment. Two-stroke arm movements toward defined targets were made in the horizontal plane on an x-y digitizer. The direction of the first segment was an elbow extension movement away from the trunk. The direction of the second segment varied between forearm extension and flexion movements. Two different indexes of difficulty (IDs) of the first segment and two of the second segment were created by varying target size. In the low ID condition for the first segment, movement duration of the initial segment lengthened and peak velocity decreased when the ID of the second segment was increased, and this pattern was found for both the extension-extension and extension-flexion sequences. In contrast, when the level of difficulty was high for the first segment, the interdependencies disappeared for the extension-extension sequence: movement duration and peak velocity were unaffected by the difficulty of the second segment. For the extension-flexion sequence, however, the interdependencies were found in the movement time of the initial segment but were eliminated in the peak velocity, i.e., movement time increased, but the peak velocity did not change. Furthermore, for both the extension-extension and extension-flexion sequences, the intersegment interval was lengthened as the level of difficulty increased. These findings suggest that difficulty of the initial segment affects how the motor planning/organization processes treat adjacent segments of the sequence. In particular, the data support the hypothesis that when the initial movement segment has a high index of difficulty, motor planning/organization processes appear to treat the adjacent segments separately as two discrete actions.
Adult↗
Comparison of human and automatic segmentations of kidneys from CT images.
PURPOSE: A controlled observer study was conducted to compare a method for automatic image segmentation with conventional user-guided segmentation of right and left kidneys from planning computerized tomographic (CT) images. METHODS AND MATERIALS: Deformable shape models called m-reps were used to automatically segment right and left kidneys from 12 target CT images, and the results were compared with careful manual segmentations performed by two human experts. M-rep models were trained based on manual segmentations from a collection of images that did not include the targets. Segmentation using m-reps began with interactive initialization to position the kidney model over the target kidney in the image data. Fully automatic segmentation proceeded through two stages at successively smaller spatial scales. At the first stage, a global similarity transformation of the kidney model was computed to position the model closer to the target kidney. The similarity transformation was followed by large-scale deformations based on principal geodesic analysis (PGA). During the second stage, the medial atoms comprising the m-rep model were deformed one by one. This procedure was iterated until no changes were observed. The transformations and deformations at both stages were driven by optimizing an objective function with two terms. One term penalized the currently deformed m-rep by an amount proportional to its deviation from the mean m-rep derived from PGA of the training segmentations. The second term computed a model-to-image match term based on the goodness of match of the trained intensity template for the currently deformed m-rep with the corresponding intensity data in the target image. Human and m-rep segmentations were compared using quantitative metrics provided in a toolset called Valmet. Metrics reported in this article include (1) percent volume overlap; (2) mean surface distance between two segmentations; and (3) maximum surface separation (Hausdorff distance). RESULTS: Averaged over all kidneys the mean surface separation was 0.12 cm, the mean Hausdorff distance was 0.99 cm, and the mean volume overlap for human segmentations was 88.8%. Between human and m-rep segmentations the mean surface separation was 0.18-0.19 cm, the mean Hausdorff distance was 1.14-1.25 cm, and the mean volume overlap was 82-83%. CONCLUSIONS: Overall in this study, the best m-rep kidney segmentations were at least as good as careful manual slice-by-slice segmentations performed by two experienced humans, and the worst performance was no worse than typical segmentations from our clinical setting. The mean surface separations for human-m-rep segmentations were slightly larger than for human-human segmentations but still in the subvoxel range, and volume overlap and maximum surface separation were slightly better for human-human comparisons. These results were expected because of experimental factors that favored comparison of the human-human segmentations. In particular, m-rep agreement with humans appears to have been limited largely by fundamental differences between manual slice-by-slice and true three-dimensional segmentation, imaging artifacts, image voxel dimensions, and the use of an m-rep model that produced a smooth surface across the renal pelvis.
Humans↗
Vertebroplasty and kyphoplasty affect vertebral motion segment stiffness and stress distributions: a microstructural finite-element study.
STUDY DESIGN: The mechanical behavior of a thoracic motion segment following cement augmentation was studied using the finite-element method. OBJECTIVE: To examine effects of cement augmentation on motion segment stiffness and load transfer. SUMMARY OF BACKGROUND DATA: Vertebroplasty and kyphoplasty procedures are meant to stiffen and strengthen the vertebral body, but the optimal cement volume and placement to achieve these goals without altering load transfer to adjacent segments are unknown. METHODS: A microstructural finite-element model of a vertebral motion segment was constructed from micro-CT images. Microdamage within the vertebral body trabecular structure was modeled using an elasto-plastic modulus reduction scheme. Three motion segment damage models were created: I = 18% apparent modulus reduction (least damage), II = 45%, and III = 85% (most damage); and several one- and two-segment polymethylmethacrylate cement repair strategies (partial fill kyphoplasty, replacement of bone and marrow; and both partial fill and complete fill vertebroplasty, replacement of marrow only) were studied. Average disc and bone stresses and motion segment apparent compressive stiffness were compared with baseline (undamaged and untreated) simulation results. RESULTS: In terms of maximizing stiffness and minimizing stress alterations in the adjacent vertebral body and increasing motion segment apparent stiffness, we found that, other than complete fill, the most effective single-segment cement repair strategy was vertebroplasty on the periphery of the superior segment overlying the disc anulus (<0.1% overall vertebral body bone stress alteration and 83% stiffness increase, respectively, damage Model III). Two-segment vertebroplasty (all repair models) restored motion segment stiffness to baseline levels in all damage models, while single-segment vertebroplasty (all repair models) restored stiffness to baseline levels only in damage Model I. Single- and two-segment kyphoplasty was effective in restoring stiffness to baseline levels for Model I only. Compared with the baseline model, cement augmentation decreased average treated segment bone stresses (up to 66%, complete fill vertebroplasty elasto-plastic modulus reduction Model III), increased average intervertebral disc nucleus stresses (up to 59%, kyphoplasty elasto-plastic modulus reduction Model III), and increased average adjacent segment, endplate region stresses (up to 2.8%, kyphoplasty elasto-plastic modulus reduction Model II). Adjacent (untreated) segment peak bone stresses were increased (up to 45%, kyphoplasty, Model III) in endplate regions underlying the intervertebral disc nucleus. CONCLUSIONS: The damage-repair simulations indicated that cement augmentation improves motion segment stiffness but substantially alters bone stress distributions in treated and adjacent segments.
Aged↗
Segment difficulty in two-stroke movements in patients with Parkinson's disease.
In the horizontal plane on a digitizer tablet, subjects made an elbow-extension, two-stroke movement away from the trunk to a first target and then on to a second target. If the two segments of the movement were executed in an integrative manner, the accuracy constraint on the first segment should have produced changes in kinematic features not only of that segment but also of the second segment. Two-stroke movements of ten Parkinson's disease (PD) patients and ten controls were studied to examine whether a high-accuracy constraint on the first segment influences the performance of the second, when the second target has either a high- or low-accuracy requirement. When the accuracy requirement of the second segment was low, both PD patients and controls showed that changing the first target size from large to small influenced the performance of not only the first segment but also the second segment. For the first segment, movement time, acceleration time, and deceleration time increased when moving to the small first target as compared to the large first target. The peak velocity and peak acceleration also decreased as the first target size decreased. For the second segment, similar patterns of kinematic changes in relation to the first segment were observed in all of these parameters. When the accuracy requirement of the second segment was high, the controls showed similar changes in the first and second segments in relation to the change of first target sizes. In contrast, the PD patients showed that the target size that defined the first movement mainly influenced the performance of that segment. Among kinematic parameters tested for the second segment, only acceleration time increased as the first target size decreased. Other parameters in general did not change, regardless of whether movement of the first segment was made to the small or large target. These results indicate that the two-stroke movements of PD patients showed little evidence that they were planned and organized in an integrative manner when there was a high-accuracy constraint imposed on the second segment. On the other hand, control subjects performed two-stroke movements in a manner that suggested the two segments were planned and organized together regardless of an accuracy constraint imposed.
Aged↗
Effects of beta-radiation with a 188rhenium-filled balloon catheter system on non-stented adjacent coronary artery segments.
BACKGROUND: The effects of beta-radiation with a (188)rhenium ((188)Re)-filled balloon catheter system on angiographically normal reference segments have not been well defined. METHODS: In the Seoul National University Post-Angioplasty Rhenium irradiation (SPARE) trial, patients with de novo or restenotic lesions were first treated with a conventional catheter-based technique and then randomized to either a radiation group or a control group. Irradiation was performed using a (188)Re-filled conventional balloon catheter system. Among 97 radiation group enrolled in this study from April 1998 through May 2001, 20 patients with de novo lesions who received brachytherapy with a balloon at least 10 mm longer than the length of an implanted stent, were selected and their post-intervention and follow-up intravascular ultrasound (IVUS) images were analyzed. Each reference segment was divided into two segments; full dose-irradiation with injury segment (irradiated segment; from the stent edge to the radiopaque balloon markers), and low dose-irradiation without injury segment (edge segment; 5-mm long segment proximal or distal to the location of radiopaque markers). In control group, serial IVUS analysis was available only in 10 patients, and IVUS parameters of the non-stented adjacent segments in these patients were compared to those of irradiated segments in radiation group patients. RESULTS: Forty irradiated and 38 edge segments of the 20 radiation group patients were analyzed. In proximal irradiated segments, no significant changes were found in external elastic membrane (EEM), lumen or in the plaque plus media (P&M) areas. In distal irradiated segments, significant increases in the EEM (12.5+/-4.5 to 14.0+/-5.0 mm(2), P<0.01) and P&M areas (5.5+/-2.0 to 6.6+/-2.3 mm(2), P<0.01) were found to occur without a change in lumen area. In proximal edge segments, P&M areas were significantly increased (9.0+/-1.7 to 10.5+/-2.6 mm(2), P=0.03). No significant changes in EEM, lumen or P&M areas were observed in the distal edge segments. Comparisons between the irradiated segments (n=40) in the radiation group and the non-stented adjacent segments (n=19) in the control group showed a significant difference in the percentage change of EEM areas (18.5+/-33.2% in radiation group vs. -3.1+/-32.1% in control group, P=0.02). CONCLUSIONS: beta-radiation with a (188)Re-filled conventional balloon catheter system appears to have no significant deleterious effect on angiographically normal reference segments over a 6 months follow up after brachytherapy.
Aged↗
An anatomy-based beam segmentation tool for intensity-modulated radiation therapy and its application to head-and-neck cancer.
PURPOSE: In segmental intensity-modulated radiation therapy (IMRT), the beam fluences result from superposition of unmodulated beamlets (segments). In the inverse planning approach, segments are a result of ''clipping'' intensity maps. At Ghent University Hospital, segments are created by an anatomy-based segmentation tool (ABST). The objective of this report is to describe ABST. METHODS AND MATERIALS: For each beam direction, ABST generates segments by a multistep procedure. During the initial steps, beam's eye view (BEV) projections of the planning target volumes (PTVs) and organs at risk (OARs) are generated. These projections are used to make a segmentation grid with negative values across the expanded OAR projections and positive values elsewhere inside the expanded PTV projections. Outside these regions, grid values are set to zero. Subsequent steps transform the positive values of the segmentation grid to increase with decreasing distance to the OAR projections and to increase with longer pathlengths measured along rays from their entrance point through the skin contours to their respective grid point. The final steps involve selection of iso-value lines of the segmentation grid as segment outlines which are transformed to leaf and jaw positions of a multileaf collimator (MLC). Segment shape approximations, if imposed by MLC constraints, are done in a way that minimizes overlap between the expanded OAR projections and the segment aperture. RESULTS: The ABST procedure takes about 3 s/segment on a Compaq Alpha XP900 workstation. In IMRT planning problems with little complexity, such as laryngeal (example shown) or thyroid cancer, plans that are in accordance with the clinical protocol can be generated by weighting the segments generated by ABST without further optimization of their shapes. For complex IMRT plans such as paranasal sinus cancer (not shown), ABST generates a start assembly of segments from which the shapes and weights are further optimized. CONCLUSIONS: ABST is a fast procedure to generate a set of segments for IMRT planning. The plan is finalized by assigning weights to the segments or by direct optimization of segment shapes and weights. ABST allows us to avoid the step of translating optimized intensity maps to sequences of segments.
Algorithms↗
Gross quantitative measurements of spinal cord segments in human.
STUDY DESIGN: Anatomical measurement. OBJECTIVE: To obtain quantitative anatomical data on each spinal cord segment in human, and determine the presence of correlations between the measures. SETTING: Department of Rehabilitation Medicine, Pusan National University Hospital, Pusan, Korea. METHODS: A total of 15 embalmed Korean adult human cadavers (13 males, two females; mean age 57.3 years) were used. The length of each cord segment was defined as the root attachment length plus the upper inter-root length. After performing a total vertebrectomy, a transverse cut was made at the approximate proximal and distal point of each segment from segment C3 to S5. Sagittal and transverse diameters at the proximal end of each segment, and cross-sectional area, height, and volume of the segment were measured. RESULTS: The transverse diameter was largest at segment C5, and decreased progressively to segment T8. However, the sagittal diameter of each segment did not change distinctly with the segment. The cervical and lumbar enlargements were determined by the transverse diameters of the segments. Segment C5 had the largest cross-sectional area, at 75.0 mm(2). Segment T6 was the longest, averaging 22.4 mm in length. The longest segment in the cervical spinal cord was segment C5, at 15.5 mm, and segment L1 in the lumbar spinal cord. The volume was largest at segment C5, with a value of 1173.9 mm(3). CONCLUSIONS: We found characteristic quantitative differences in the values of the parameters measured in the thoracic spinal cord compared to those measured in the cervical and lumbar or lumbosacral spinal cords. These measurements of spinal cord segments appear to provide valuable and practical standard quantitative features and may provide basic data for understanding the morphometric characteristics relevant to pathophysiologic conditions of the spinal cord.
Cervical Vertebrae↗
Comparison of the main oesophageal pathophysiological characteristics between short- and long-segment Barrett's oesophagus.
AIM: To assess the oesophageal manometric characteristics and 24-h pH profiles of patients with both short-segment and long-segment Barrett's oesophagus and compare them with those of patients with reflux oesophagitis and controls. METHODS: Seventy-nine patients who had undergone upper digestive endoscopy were recruited: 16 had short-segment Barrett's oesophagus, 13 had long-segment Barrett's oesophagus, 25 had grade III oesophagitis according to the Savary-Miller classification and 25 were used as controls. The diagnosis of Barrett's oesophagus was based on the histological detection of specialized intestinal metaplasia, which extended < 3 cm into the oesophagus in patients with short-segment disease and > 3 cm in patients with long-segment disease. All subjects underwent oesophageal manometry and basal 24-h oesophageal pH monitoring. RESULTS: The lower oesophageal sphincter pressure was significantly lower in patients with reflux oesophagitis and short-segment and long-segment Barrett's oesophagus than in controls (P=0.0004-0.0001), but there was no difference among the three reflux groups. The peristaltic wave amplitude of patients with long-segment Barrett's oesophagus was significantly lower than that of controls (P=0.002) and patients with short-segment Barrett's oesophagus (P=0.02), but was no different from that of patients with reflux oesophagitis. The percentage of non-propagated wet swallows was significantly higher in patients with reflux oesophagitis and short-segment and long-segment Barrett's oesophagus when compared with that of controls (P=0.0004-0.0001). The total percentage of time the oesophagus was exposed to pH < 4.0 was significantly higher in patients with reflux oesophagitis and short-segment and long-segment Barrett's oesophagus (P=0.0001) than in controls, and was higher in patients with long-segment disease than in those with short-segment disease (P=0.01). CONCLUSIONS: Long-segment Barrett's oesophagus is characterized by a greater impairment of peristaltic wave amplitude and a higher oesophageal acid exposure than is short-segment Barrett's oesophagus. However, both forms are linked to increased acid reflux.
Adult↗
Post-transplant changes of segment 4 after living related liver transplantation.
The purpose of this study was to evaluate the outcome of the medial segment of the graft after living related liver transplantation (LRLT). Of the 12 pediatric recipients who underwent LRLT, 2 received whole left liver graft, 1 left lateral segment graft, and 9 extended left lateral segment grafts. The hepatic veins of the donor were reviewed and the volume of the medial segment and left lateral liver was measured before and 6 months after liver transplantation. The flow velocity and direction of the portal vein in the medial segment graft was also evaluated by Doppler ultrasound. The grafted livers of all recipients showed a substantial increase in volume of 9-120% 6 months after LRLT. For the left lateral segment, an increase in volume was found in all cases ranging from 21 to 245%. For the medial segment, volume increases of 5-48% were found in seven cases with normal hepatopetal flow detected inside the segment 4 intrahepatic portal vein. In four cases, the partial medial segment graft of the extended left lateral liver graft decreased in volume from 33 to 69%. Among these four cases, slow flow (n = 2) and hepatofugal flow (n = 1) were also detected in the intrahepatic portal vein of the medial segment. Mapping of the tributary of the hepatic veins of the graft revealed inadequate venous drainage of the partial segment 4 graft, which may be considered as the cause of the atrophic change of the partial segment 4 graft. In conclusion, different regenerative rates between the left lateral segment and the medial segment were noted, with a greater rate in the left lateral segment. The venous drainage of the medial segment is of primary concern in the determination of the outcome of the regeneration. Atrophic change occurs when inadequate hepatic venous drainage is encountered. Therefore, if an extended left lateral liver graft is required, the corresponding draining veins of the partial medial segment must be preserved. Otherwise, whole left liver or left lateral segment graft would be a better choice.
Blood Flow Velocity↗