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PubMed2002

Appearance-based segmentation of medial temporal lobe structures.

A new paradigm for the characterization of structure appearance is proposed, based on a combination of gray-level MRI intensity data and a shape descriptor derived from a priori principal components analysis of 3D deformation vector fields. Generated without external intervention, it extends into 3D more classic, 2D manual landmark-based shape models. Application of this novel concept led to a method for the segmentation of medial temporal lobe structures from brain magnetic resonance images. The strategy employed for segmentation aims at synthesizing, using the appearance model, a deformation field that maps a new volume onto a reference target. Any information defined on the reference can then be propagated back on the new volume instance, thereby achieving segmentation. The proposed method was tested on a data set of 80 normal subjects and compared against manual segmentation as well as automated segmentation results from ANIMAL, a nonlinear registration and segmentation technique. Experimental results demonstrated the robustness and flexibility of the new method. Segmentation accuracy, measured by overlap statistics, is marginally lower (< 2%) than ANIMAL, while processing time is six times faster. Finally, the applicability of this concept toward shape deformation analysis is presented.

Algorithms↗
PubMed2003

Functional specialization of the axon initial segment by isoform-specific sodium channel targeting.

Voltage-dependent sodium channels cluster at high density at axon initial segments, where propagating action potentials are thought to arise, and at nodes of Ranvier. Here, we show that the sodium channel Na(v)1.6 is precisely localized at initial segments of retinal ganglion cells (RGCs), whereas a different isoform, Na(v)1.2, is found in the neighboring unmyelinated axon. During development, initial segments first expressed Na(v)1.2, and Na(v)1.6 appeared later, approximately in parallel with the onset of repetitive RGC firing. In Shiverer mice, Na(v)1.6 localization at the initial segment was unaffected, although Na(v)1.6 expression was severely disrupted in the aberrantly myelinated optic nerve. Targeting or retention of Na(v)1.6 requires molecular interactions that normally occur only at initial segments and nodes of Ranvier. Expression at nodes but not initial segments exhibits an additional requirement for intact myelination. Because of their high density at the initial segment, Na(v)1.6 channels may be crucial in determining neuronal firing properties.

Animals↗
PubMed2003

[A new method for measuring dentition segments and the diagnosis of their occlusion].

A new method for evaluation of dentition during occlusion is suggested (2001). Thirty patients with normal occlusion were examined. Dental occlusion was evaluated for the frontal and lateral segments. Frontal and lateral (right and left) segments of the upper and lower teeth were examined, The upper and lower segments differed in size: the mean size of the upper frontal segment was 37.7 +/- 1.7 mm, that of the lower frontal segment 36.2 +/- 1.7 mm. The proportionality index was 1.04. The lateral segments of the upper and lower teeth were equal, their mean size being 20.2 +/- 0.8 mm. Hence, measurements of dentition segments during occlusion help evaluate their proportionality and detect changes in their sizes in patients with maxillodental abnormalities.

Anthropometry↗
PubMed1992

[Usefulness of segmental Lp-TAE using lipiodol mixed with anticancer agent for inoperable hepatocellular carcinoma].

To determine the effect of appraising subsegmental or segmental transarterial embolization with Lipiodol mixed with anticancer drugs followed by gelatin particles (Segmental Lp-TAE) on inoperable hepatocellular carcinoma, we examined CT patterns and therapeutic results in 57 patients after Segmental Lp-TAE. Fifty-six tumors including 47 tumors less than 5 cm in size were the nodular type and 1 tumor was the massive type. The mean tumor size was 3.6 cm and the mean amount of Lipiodol was 4.4 ml. Portal veins in the embolized segment were highly visualized by injected Lipiodol on plain film immediately after Segmental Lp-TAE. On the follow-up CT, the size of the tumor with dense Lipiodol accumulation were reduced in all cases, and atrophy of the embolized segment was recognized. Forty-four of the 57 patients are alive, with the longest surviving patient still alive at 4 years and 5 months. Seventeen patients have survived for more than 2 years (direct crude survival rate: 65.0%), with the cumulative survival rates 93.2% at 1 year, 71.6% at 2 years. No recurrence was recognized in 33 of the 41 patients (80.0%) that were followed up for more than 1 year after Segmental Lp-TAE is a useful therapeutic method for hepatocellular carcinoma.

Aged↗
PubMed2003

[Segmental tibia fractures: a critical retrospective analysis of 49 cases].

PURPOSE OF THE STUDY: Segmental tibia fracture is defined by the presence of two distinct fracture lines separating the cortical and completely isolating an intermediary segment of the tibia. Little work has been published on this clinical entity. We report a retrospective analysis of 49 patients treated in one center for segmental tibia fracture in order to determine more precisely the indications for three surgical techniques: locked intramedullary nailing with or without reaming, and external fixation. MATERIAL AND METHODS: The series included 34 men and 15 women, mean age 40.8 years. All patients had traffic accident: 25 had multiple fractures, 17 had multiple organ injury, and 9 had floating knees. There were 30 open fractures; 2 patients developed compartment syndrome. The segments were: distal-proximal metaphyso-metaphyseal (n=1), proximal diaphyso-metaphyseal (n=17), diaphyso-diaphyseal (n=27), and distal diaphyso-metaphyseal (n=4). The mean length of the intermediary segment was 14.1 cm. The emergency procedure involved intramedullary nailing with reaming (Grosse-Kempf nail) in 32 patients, intramedullary nailing without reaming in 7 patients (Collin nail in 5 and UTN in 2) and external fixation with non-transfixing pins in 10 patients (Orthofix). External fixation was converted early to intramedullary nailing in three patients (Grosse-Kempf nail in 2 and Collin nail in 1). RESULTS: Three patients were excluded: 2 underwent amputation after failure of vessel repair and 1 developed septic necrosis of a free latissimus dorsi flap; 1 patient died from multiple organ failure. Outcome at at least 18 months was known for 42 patients (4 patients lost to follow-up). There were 4 cases of post-nailing compartment syndrome; one case of deep infection on a Grosse-Kempf nail was treated by external fixation. Among the 27 patients with segment tibia fractures finally stabilized with a Grosse-Kempf nail, nonunion developed in 8; mean time to bone healing was 10 +/- 4.8 months (with dynamization in 13 patients). For the 7 external fixations, nonunion developed in 2; mean time to bone healing was 9.2 +/- 2.9 months. For the 8 nailings without reaming, nonunion developed in 2; mean time to bone healing was 9.5 +/- 2.5 months. Bone healing was not simultaneous in the two foci in more than half of patients. Two patients developed clinical sequelae of their compartment syndrome with deficient knee flexion in two. The 12 cases of aseptic nonunion were successfully treated by nailing with reaming and early weight bearing. DISCUSSION: Comparing our results with the therapeutic modalities used in published reports on segmentary tibia fractures showed that time to bone healing and the rate of nonunion were generally greater than in our series. A critical analysis of these results allows us to propose a more interventionalistic attitude before the development of late healing. We also propose a classification of segmental tibia fractures and a decisional tree for choosing between the three techniques based on the presence of soft tissue damage, the presence of compartment syndrome (nailing without reaming), and the presence of proximal or distal metaphyseal fractures (distal locked nail). Nailing with moderate reaming remains the preferred method.

Adolescent↗
PubMed2003

Vertebrate somitogenesis: a novel paradigm for animal segmentation?

In vertebrates, the primary segmented tissue of the body axis is the paraxial mesoderm, which lies bilaterally to the axial organs, neural tube and notochord. The segmental pattern of the paraxial mesoderm is established during embryogenesis through the production of the somites which are transient embryonic segments giving rise to the vertebrae, the skeletal muscles and the dorsal dermis. Somitogenesis can be subdivided into three major phases (see Fig. 1). First a growth phase during which new paraxial mesoderm cells are produced by a growth zone (epiblast and blastopore margin or primitive streak and later on tail bud) and become organized as two rods of mesenchymal tissue,forming the presomitic mesoderm. Second a patterning phase occuring in the PSM, during which the segmental pattern is established at the molecular level. Third, the somitic boundaries are formed during the morphological segmentation phase. In all vertebrates, all cells of the paraxial mesoderm, during their maturation in the PSM, go successively through these three phases, which are tightly regulated at the spatio-temporal level. The first phase of paraxial mesoderm production falls out of the scope of this review, as it essentially pertains to the gastrulation process. Here, I essentially discuss the segmental patterning phase in vertebrates. Recent data suggest that establishment of the segmental pattern relies on a clock and wavefront mechanism which has been conserved in vertebrates. Furthermore, conservation of this system could extend to invertebrates, suggesting that the clock and wavefront is an ancestral mechanism.

Animals↗
PubMed2003

[Assessment of left ventricular ejection fraction and wall motion in patients after myocardial infarction with and without persistent electrocardiographic ST-segment elevation--using gated radionuclide angiography].

UNLABELLED: In everyday practice two-dimensional echocardiography is a routine method used to diagnose left ventricular (LV) wall motion abnormalities and determine ejection fraction (EF). However, in some patients, for technical reasons, it is possible to apply only apical projections and EF and LV wall motion abnormalities cannot be therefore obtained. The aim of the study was to measure LV EF and wall motion abnormalities in the patients healed from MI, with and without persistent electrocardiographic ST segment elevation, in whom echocardiographic diagnosis was difficult. LV wall motion abnormalities and EF were determined using non-invasive method--gated radionuclide angiography. Gated radionuclide angiography was performed in 45 patients, 3 months after previous anterior MI. The study was acquired after technetium 99mTc red cell labeling in vivo. The data were collected using a Toshiba scintillation gamma camera with a MODUMED computer system coupled with a gating device. Patients were divided into two groups. Group I consisted of 24 patients with persistent electrocardiographic ST segment elevation and group II--of 21 patients without persistent elevation of this segment. RESULTS: In the group I, left ventricular ejection fraction ranged between 10 and 36% (mean: 24%). In 9/24 patients (38%) diffuse hypokinesis, in 7/24 patients (29%) regional akinesis and in the last 8/24 patients (33%) regional dyskinesis with impaired dilated left ventricular systolic and diastolic function were observed. In the group II, left ventricular ejection fraction ranged from 19 to 47%. Mean value of this parameter equaled 32% and was statistically significantly higher than in patients from group II. In 9/21 patients (42%) diffuse hypokinesis, in 2/21 patients (10%) regional anterior wall hypokinesis with the normal function of other walls, and in the last 10/21 patients (48%) regional anterior wall akinesis with the diffuse hypokinesis of other walls were localized. In the patients without persistent electrocardiographic ST segment elevation, diffuse hypokinesis was observed in majority of cases. In none of those patients ventricular aneurysm was diagnosed. In the patients with persistent electrocardiographic ST segment elevation, three types of decreased left ventricular function (diffuse hypokinesis, regional akinesis and ventricular aneurysm) were observed. It should be noted that in 1/3 of those patients ventricular aneurysm was diagnosed. Presence of diskinetic wall motion abnormalities in group I (in 8/24 patients) was statistically significantly more frequent (p < 0.01) than in group II (in 0/21 patients). CONCLUSIONS: 1. Presence of persistent electrocardiographic ST segment elevation in a patient with post infarction myocardial failure is a prerequisite for suspicion of post myocardial infarction left-ventricular aneurysm. 2. In patients without persistent electrocardiographic ST segment elevation and post infarction myocardial failure diffuse hipokinesis (sometimes with regional akinesis) is predominantly observed.

Adult↗
PubMed1992

Segmental mediolytic arteritis involving hepatic arteries.

Segmental mediolytic arteritis is a rare, noninflammatory arteriopathy that involves the splanchnic arteries of adults with shock and the coronary arteries of neonates with hypoxemia. We report the first case (to our knowledge) of segmental mediolytic arteritis involving the hepatic arteries. The lesion begins with cytoplasmic vacuolar degeneration of the arterial smooth-muscle cells, which then progresses to coalescence of vacuoles, leading to disruption of the media, intramural hemorrhage, and periadventitial fibrin deposition. Segmental mediolysis results in arterial wall defects, which can lead to dissecting aneurysms or hemorrhage due to arterial rupture. The intima and internal elastica are spared from the lytic process, and there is minimal periadventitial inflammation. Segmental mediolytic arteritis is not a true arteritis; therefore, segmental mediolytic arteriopathy may be a preferable term. Morphological similarities exist between segmental mediolytic arteritis and arterial fibromuscular dysplasia. In our case, hepatic ischemia correlated with mediolysis involving the hepatic arterial branches. Segmental mediolytic arteritis is thought to be due to an inappropriate vasospastic response, developing in the setting of hypoperfusion and hypoxemia.

Aged↗
PubMed2005

[Image segmentation in tongue characterization].

Tongue diagnosis is one of the essential methods of traditional Chinese medical diagnosis. The accuracy of tongue diagnosis can be improved by tongue characterization. Tongue area segmentation and homogeneous regions segmentation in tongue are important contents of preprocess of tongue image. An algorithm based on edge detection and Gradient vector flow (GVF) active contour for tongue area segmentation and another algorithm based on unsupervised segmentation of color-texture for homogeneous regions segmentation in tongue were presented. Totally about 1500 tongue images were collected. Results of tongue area segmentation achieved accuracy rate of 94.3% and results of homogeneous regions segmentation in tongue were approved by traditional Chinese medical experts. The experiments results show robustness of the algorithms. This work establishes solid foundation for feature selecting of Tongue diagnosis.

Algorithms↗
PubMed2006

[Segmental and bisegmental resections of liver in a treatment of malignant neoplasms].

UNLABELLED: The news in understanding intrahepatal anatomy, such as radiology contemporary technology making easier segmental and bisegmental access to hepatal resection. This access comprises resection of isolated anatomical segments or a sector of liver which is depends of magnitude of intrahepatal pathological process. After segmental or bisegmental resection of liver, patients were analysed in the period from 15 and 30 days after the operation. Analysis of patients from this period comprise: localisation of tumour in relation on segments, liver test and follow up, technique of resection, intraoperative stream, the period of operation, blood follow up through v. portae, blood loss and quantitative and qualitative analysis of postoperative complications. RESULTS: between January 2000 and March 2005, sixty two subject were analysed that have been operated on our clinic (segmental or bisegmental resection), because of the metastatic process of liver and hepatocellular carcinoma of liver (HCC). Hospital mortality was 2.1%, with most often mortality in patients with HCC and cirrhosis of liver. High of morbidity from this period were 19,8%. Need for transfusion of blood (fresh erythrocytes) were 1,2 +/- 0,5 U. Patients with HCC had more needs from blood transfusions contrary patients without HCC; 2,9 +/- 1,4 contrary 0,7 +/- 0,28 U (p<0,05). Recidivism of malignant process in hepatal margin were 2,7%. CONCLUSION: Segmental hepatal resection is very accurate technique which makes possible complete resection of tumour and in the same time preservation of healthy liver parenchyma. Segmental hepatal resection is especially useful for patients with HCC and patients with recidivism or progress of primary process.

Carcinoma, Hepatocellular↗
PubMed2006

ST segment elevation in lead aVR and coronary artery lesions in patients with acute coronary syndrome.

INTRODUCTION: Recently, the prognostic value of ST segment elevation in lead aVR in acute coronary syndrome (ACS) and its relationship with significant stenosis of the left main coronary artery (LMCAS) and three-vessel disease have been highlighted. AIM: Analysis of the relationship between ST segment elevation observed in aVR lead and angiographic severity of coronary artery disease in patients with ACS. METHODS: The study involved 134 patients with ACS, including 54 subjects with ST elevation in aVR (group A) and 80 patients without elevation of ST in the same lead (group B), aged 33-78 years, mean 59.9+/-9.7 years. The severity of coronary artery disease was compared between the two groups. The logistic regression model was used for the analysis of factors affecting ST segment in aVR, as well as LMCAS and three-vessel disease probability. RESULTS: In patients with ST elevation in aVR, three-vessel disease prevalence was two times higher (61.1% vs 35.0%; p <0.01), and LMCAS - three times higher (55.6% vs 17.5%; p <0.000001) than in those without ST elevation in aVR. Factors independently associated with ST elevation in aVR were LMCAS (OR 6.1; 95% CI 2.62-14.23; p <0.00005), ST segment elevation in V1 (OR 3.03; 95% CI 1.34-6.86; p <0.01) and diabetes (OR 2.89; 95% CI 1.17-7.15; p <0.05). The predictors of LMCAS were three-vessel disease and ST elevation in aVR, while the predictors of three-vessel disease were: LMCAS, diabetes, male gender and history of myocardial infarction. CONCLUSIONS: Elevation of the ST segment in aVR in the setting of acute coronary syndrome identifies patients with severe coronary artery disease. Only left main coronary artery disease, however, remains independently associated with ST segment elevation in aVR. Three-vessel disease and the left main coronary artery stenosis equivalent are not independent predictors of ST segment elevation in aVR of standard electrocardiograms recorded in patients with acute coronary syndrome.

Acute Disease↗
PubMed2006

Rediscovering market segmentation.

In 1964, Daniel Yankelovich introduced in the pages of HBR the concept of nondemographic segmentation, by which he meant the classification of consumers according to criteria other than age, residence, income, and such. The predictive power of marketing studies based on demographics was no longer strong enough to serve as a basis for marketing strategy, he argued. Buying patterns had become far better guides to consumers' future purchases. In addition, properly constructed nondemographic segmentations could help companies determine which products to develop, which distribution channels to sell them in, how much to charge for them, and how to advertise them. But more than 40 years later, nondemographic segmentation has become just as unenlightening as demographic segmentation had been. Today, the technique is used almost exclusively to fulfill the needs of advertising, which it serves mainly by populating commercials with characters that viewers can identify with. It is true that psychographic types like "High-Tech Harry" and "Joe Six-Pack" may capture some truth about real people's lifestyles, attitudes, self-image, and aspirations. But they are no better than demographics at predicting purchase behavior. Thus they give corporate decision makers very little idea of how to keep customers or capture new ones. Now, Daniel Yankelovich returns to these pages, with consultant David Meer, to argue the case for a broad view of nondemographic segmentation. They describe the elements of a smart segmentation strategy, explaining how segmentations meant to strengthen brand identity differ from those capable of telling a company which markets it should enter and what goods to make. And they introduce their "gravity of decision spectrum", a tool that focuses on the form of consumer behavior that should be of the greatest interest to marketers--the importance that consumers place on a product or product category.

Commerce↗
PubMed2006

[Automatic segmentation of three dimension medical image series].

We propose an improved version of regional competition algorithm in this paper, and apply it to the automatic segmentation of medical image series, particularly in the segmentation and recognition of brain tumor. The traditional regional competition is enhanced by combining the attractive aspects of fuzzy segmentation, and thus it provides an efficient approach to segment the fuzzy and heterogeneous medical images. In order to perform regional competition on medical image series, we utilize the segmentation result of a slice to initiate the next segmented slice, while the first slice is initialized using regional growing algorithm. Moreover, we develop an algorithm to recognize the tumors automatically, taking into account its characters. Experimental results show that our algorithm performs well on the segmentation of magnetic resonance imaging (MRI) image series with high speed and precision.

Algorithms↗
PubMed1991

[An analysis of ST segment shift in procordial leads in patients with acute inferior myocardiac infarction with and without right ventricular infarction].

ST segment change in procordial leads was analysed in 58 patients with acute inferior myocardial infarction (IMI). ST segment depression in V2 lead was negatively correlated with ST segment elevation in a VF lead in patients with IMI. ST segment depression in V2 lead was not observed when IMI was accompanied by right ventricular infarction. It indicates that ST segment depression in procordial leads was the reciprocal change of ST segment elevation in inferior leads. The direction and amplitude of ST segment shift in procordial leads may be affected by the presence of right ventricular infarction (RVI). The ratio of ST V2/ST aVF less than 0.5 may suggest a diagnosis of IMI with accompanying RVI.

Electrocardiography↗
PubMed1990

[Segmentation of the liver and anatomical variants of the portal system].

The authors, who studied 605 human livers according to various techniques, present their own anatomo-surgical conception of human liver segmentation, based on the distribution of the whole intrahepatic Glisson's system, and by dividing the liver into two hemi-livers, right and left (the term "lobe" being reserved, according to Tôn-Thât-Tùng, for the classical anatomical lobes): the right hemi-liver is subdivided into two segments: anterior and posterior; the left hemi-liver is subdivided into three segments: medial (IV), lateral-anterior (III) and lateral-posterior (II); the dorsal segment (I) or the classical Spigel's lobe tends to overlap both half livers (more on the left than on the right). The authors then describe, indicating the percentages, the typical patterns and anatomical variants of intersegmental fissures and the portal system. During the discussion, the authors say that, according to their experience, the right hemi-liver segments can be divided into some smaller units: the posterior segment into two subsegments (VI and VII) and the anterior ones into three subsegments (V, VIIIi and VIIIe); and they justify the segmental division of the left hemi-liver. The authors conclude that statistical and analytical study can define a typical anatomical pattern but that, owing to many anatomical variants, it is easier to perform the transparenchymal approach to the vasculo-biliary structures, enveloped in the same Glisson's capsule, rather than to make long and dangerous dissections at the porta hepatis.

Humans↗
PubMed1989

Regulation of proacrosin conversion in isolated guinea pig sperm acrosomal apical segments.

Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, proacrosin has been identified in extracts of intact guinea spermatozoa as a major silver staining band which reacted immunologically with antibodies made against purified proacrosin from guinea pig testis. Proacrosin exhibited an approximate Mr of 50,000 and was rapidly converted to an Mr 45,000 protein following induction of the acrosome reaction with 2.0 mM CaCl2 and 1 micrograms/ml A23187. Apical segments isolated at pH 6.0 from guinea pig spermatozoa also contained a major silver staining band of Mr 50,000 which cross-reacted with antibodies to guinea pig testis proacrosin. Subcellular fractionation of spermatozoa indicated that proacrosin remained in the particulate fraction of homogenized spermatozoa and was enriched within the isolated acrosomal apical segment. When apical segments isolated at pH 6.0 were incubated at pH 7.5, proacrosin was rapidly converted to the Mr 45,000 form observed in spermatozoa undergoing the acrosome reaction. The conversion process in isolated apical segments was inhibited by leupeptin and was accelerated in the presence of calcium, magnesium, and manganese. Zinc completely inhibited the conversion of proacrosin to the Mr 45,000 protein. Neither proacrosin nor the Mr 45,000 protein were released into the supernatant fluid during the incubation of apical segments at pH 7.5. Furthermore, the proteins were resistant to solubilization by 150 mM NaCl and 1% Triton X-100 but were solubilized by treatment of apical segments with 1 M NaCl. These results provide evidence as to the identity and subcellular distribution of proacrosin in intact guinea pig sperm prior to zymogen conversion and suggest that isolated apical segments exhibit a subset of the exocytotic reactions leading to completion of the acrosome reaction.

Acrosin↗
PubMed1989

[Segmental arterio-portal chemo-embolization in hepatocellular carcinoma (cement therapy)].

When a large amount of iodized oil (LPD) is selectively administered to targeted segments of the liver, the tumor vessels and sinusoids around the tumor are filled with LPD, subsequently regurgitating excessive LPD via the hepatic arterioportal communication into the portal branches surrounding the tumor. Segmental arterioportal chemoembolization in HCC with Doxorubicin-in-oil emulsion (DOE), which we named cement therapy, was performed in 18 patients with HCC. DOE was administered selectively into one segment division of Couinaud in ten patients, two segments in seven and three segments in one. Computed tomography and ultrasonography following the cement therapy revealed an overall response rate of 39%. The one-year cumulative survival rate was 80%, and that for three-years was 33%. Three cases underwent segmental hepatectomy and these specimens revealed total necrosis of the main tumor and whole daughter nodules, followed by various degrees of hepatic parenchymal infarction. This cement therapy realizes the simultaneous chemoembolization via the artery and portal vein, and was considered an effective treatment for extra-capsular infiltration and daughter nodules of HCC nourished by the portal vein blood flow. Limited administration of DOE to the targeted segments enables transarterial oily chemoembolization (TOCE) without any serious side effects.

Adult↗
PubMed1989

Postnatal development of the photoreceptor inner segment of the retina in dogs.

In dogs, the retina develops during the postnatal period in a manner similar to that in other animals born with closed eyelids. Photoreceptor inner segments are initially observed as a cytoplasmic bulge protruding sclerad through the external limiting membrane. Outer segment formation begins when a centriole within the inner segment attaches to the distal inner segment cell membrane. A few round mitochondria are observed within the early inner segments. As maturation proceeds, the number of mitochondria within the inner segments increases and the mitochondria elongate, orienting parallel to the long axis of the inner segment.

Animals↗