Perimeter Measurements Research Articles

TCT-768 Novel use of Aortic Valve IVUS to Guide Transcatheter Aortic Valve Implantation

Background: Accurate imaging of the aortic anatomy during Transcatheter Aortic Valve Implantation (TAVI) is important as poor valve sizing may adversely affect patient outcomes. Methods: The aim of this study was to evaluate the feasibility of a using a large field intravascular ultrasound (IVUS) catheter (Visions PV0.35,Volcano corporation,San Diego, CA) to guide valve sizing in TAVI. The catheter has a maximum imaging diameter of 60 mm (as compared to <20 mm for coronary IVUS) and uses 10MHz frequency ultrasound. The catheter is 8.5F sheath compatible and advanced in an over-the-wire technique over a 0.35 wire. Results: We performed aortic valve IVUS on 18 consecutive patients (mean age 81 3years, mean EuroSCOREII 16.6.0 8.5%, mean STS score 7.5 4.4%) for planned transfemoral TAVI with the CoreValve (Medtronic, Minneapolis, MA). IVUS imaging was performed pre-TAVI over a stiff 0.35 wire in the left ventricle. All 18 patients also had intra-procedure Trans-Oesophageal Echocardiography (TOE) and 16 of the 18 patients had pre-TAVI Multi-Detector Computed Tomography (MDCT) to guide valve sizing. All patients had successful IVUS imaging with measurement of minimum/maximum annulus diameters and annulus area/ perimeter. Of the patients who had MDCT and IVUS, the annulus measurements were compared. The mean annulus area was 398.8 80.2mm2 by IVUS and 390.4 63.7mm2 by MDCT while the mean perimeter was 79.6 6.7mm by MDCT and 79.0 8.1mm by IVUS. There was a positive correlation between the IVUS and MDCT annulus area and annulus perimeter measurements (annulus area p1⁄40.19,r1⁄40.89,95%CI 0.72-0.95;annulus perimeter p1⁄40.11, r1⁄40.91,CI 0.77-0.96) which was not statistically significant. The mean ellipticity index (EI) was greater when measured with IVUS (1.23) than when measured with MDCT (1.21,p1⁄40.03). Also of interest was IVUS imaging post TAVI which demonstrated valve leaflet function as well as frame expansion. There were no procedural complications associated with the use of this technique. Conclusions: Using IVUS to guide TAVI is feasible and warrants further evaluation and comparison with other multi-modality imaging. The technique is fast, safe and intuitive to operators with experience in coronary IVUS.

Perimetric evaluation of saccadic latency, saccadic accuracy, and visual threshold for peripheral visual stimuli in young compared with older adults.

Using a novel automated perimetry technique, we tested the hypothesis that older adults will have increased latency and decreased accuracy of saccades, as well as higher visual thresholds, to peripheral visual stimuli when compared with younger adults. We tested 20 healthy subjects aged 18 to 30 years ("young") and 21 healthy subjects at least 60 years old ("older") for detection of briefly flashed peripheral stimuli of differing sizes in eight locations along the horizontal meridian (±4°, ±12°, ±20°, and ±28°). With the left eye occluded, subjects were instructed to look quickly toward any seen stimuli. Right eye movements were recorded with an EyeLink 1000 infrared camera system. Limiting our analysis to the four stimulus positions in the nasal hemifield (-4°, -12°, -20°, and -28°), we evaluated for group-level differences in saccadic latency, accuracy, and visual threshold at each stimulus location. Saccadic latency increased as stimulus size decreased in both groups. Older subjects had significantly increased saccadic latencies (at all locations; P < 0.05), decreased accuracies (at all locations; P < 0.05), and higher visual thresholds (at the -12°, -20°, and -28° locations; P < 0.05). Additionally, there were significant relationships between visual threshold and latency, visual threshold and accuracy, and latency and accuracy (P < 0.0001). Older adults have increased latency and decreased accuracy of saccades, as well as higher visual thresholds, to peripheral visual stimuli when compared with younger adults. Saccadic latency and accuracy are related to visual threshold, suggesting that saccadic latency and accuracy could be useful as perimetric outcome measures.

Differential GPS effectiveness in measuring area and perimeter in forested settings

This study quantifies area and perimeter measurement errors, traverse times, recording intervals, and overall time and cost effectiveness for using a mapping-grade differential Global Positioning System (GPS) receiver in forested settings. We compared two configurations including one that maximized data collection productivity (position dilution of precision (PDOP) 20, signal to noise ratio (SNR 33), and minimum elevation mask 5°) and a second that involved traditional receiver settings that was designed to improve accuracies (PDOP 6, SNR 39, and minimum elevation mask 15°). We determined that averaging 30 positions and using the settings that maximized productivity was the most time effective combination of recording interval and settings. This combination of recording interval and settings proved slightly more cost effective than other traditional surveying methods such as a laser with digital compass and string box. Average absolute per cent area errors when averaging 30 positions and using maximum settings were 2.6% and average absolute per cent perimeter errors were 2.0%. These results should help forest resource professionals more effectively evaluate GPS techniques and receiver configurations.

Isoperimetrically optimal polygons in the triangular grid with Jordan-type neighbourhood on the boundary

The digital spaces have some properties that are not present in the Euclidean space. A digitized circle do not necessarily have the smallest (digital arc length) perimeter of all objects having a given area. In digital geometry various measures of perimeter and area lead to various definitions of digital circles using the digital version(s) of the isoperimetric inequality. Usually the square grid is used as digital plane with either the cityblock or the chessboard neighbourhood relation. In this paper the triangular grid is also used with two types of neighbourhood relation that play importance in Jordan curves. We search for those (digital) objects that have optimal measures and therefore they can be considered as digital circles by our definition. We show that special, (almost) regular hexagons are Pareto optimal, i.e. they fulfil both versions of the isoperimetric inequality: they have maximal area among objects having perimeter at most a given length; and they have minimal perimeter among objects enclosing at most a certain area. The optimal objects can be build in a similar way as the Wang-spiral for the square grid.

Abstract 007: Platelet Derived Growth Factor-AA Promotes Migration of Resident Cardiac Stem Cells

Bone marrow mesenchymal stem cells modulate cardiac healing via the release of paracrine factors. Although the exact mechanisms are not yet understood, one promising approach is through the mobilization of endogenous cardiac stem cells. Recently, we reported the existence of a new type of cardiac stem cell, named Cardiac Atrial appendage Stem Cells (CASCs), that is characterized by a high aldehyde dehydrogenase expression. In this study, we hypothesized that conditioned medium from mesenchymal stem cells (MSC-CM) is able to promote migration of resident cardiac stem cells. Therefore, human cardiac fragments were cultured inside a collagen type I matrix and subjected to serum-free DMEM (control) or MSC-CM. By analysis of cell counts, perimeter and area measurements, we found that MSC-CM promoted migration of cells from cardiac fragments throughout the matrix. These migrating cells possessed stem cell properties, as shown by a clonogenicity of 21.6±4.3% (n=3) and pluripotency associated genes like Oct-4, Nanog, Dppa-3, Tbx-3, c-Myc and Klf-4. Flow cytometrical analysis showed that these cells expressed a CSC-phenotype. Further investigation demonstrated that, comparable to CASCs, migrating cells had a high aldehyde dehydrogenase activity and were able to differentiate towards cardiomyocytes. In addition, we demonstrated an extensive activation of the platelet derived growth factor receptor-α (PDGFRα) in migrating cells subjected to MSC-CM. Subsequent collagen assays indicated that pure PDGF-AA was sufficient to produce migration effects similar to MSC-CM, albeit higher PDGF-AA concentrations than measured in MSC-CM were necessary. Imatinib mesylate, a PDGFR inhibitor, was partially able to attenuate MSC-CM induced migration, pointing out that PDGF-AA might work synergistically with other factors to promote migration. In conclusion, these data demonstrate that MSC-CM stimulates migration of resident CASCs. PDGF-AA is an important paracrine factor in this process, although the synergic role of other growth factors has to be further investigated. These findings contribute to the development of future therapies in which paracrine agents can be utilized to activate the endogenous repair system of the heart.

Regrowth of the Psoas Tendon After Arthroscopic Tenotomy: A Magnetic Resonance Imaging Study

The purpose of this study was to evaluate whether the psoas tendon regenerates after arthroscopic tenotomy through the central compartment of the hip in patients with internal snapping hip. Twenty-seven patients with a snapping hip, aged 18 to 54 years (mean, 37.47 years), underwent arthroscopic tenotomy through the central compartment of the hip; all patients had symptomatic femoroacetabular impingement as well. The degree of regeneration was evaluated by preoperative and postoperative measurements of the tendon perimeter with a magnetic resonance imaging protocol in patients with more than 6 months' follow-up. In addition, function was assessed preoperatively and postoperatively with the Western Ontario and McMaster Universities Osteoarthritis Index score. Postoperative active flexion force was graded clinically between 1 and 5 with the Medical Research Council score. Eight patients had less than 6 months' follow-up, and they were excluded. The remaining 19 patients were evaluated after a mean follow-up period of 23.16 months (SD, 12.95 months). Tendon regeneration occurred in all patients. Compared with preoperative measurement, the psoas tendon circumference had recovered by 84.3% on average (55.44 ± 5.68 mm v 46.71 ± 6.05 mm, P < .001). Pain improved in all patients, and the mean Western Ontario and McMaster Universities Osteoarthritis Index score fell from 49 ± 15.9 points to 10.74 ± 11.35 points (P < .001). Muscle force recovered completely in all cases. There is a process of tissular repair after psoas tenotomy, and the findings on magnetic resonance imaging suggest that tendon tissue regrowth occurs. Level IV, therapeutic case series.

Geometric inequalities in Carnot groups

Let $\GG$ be a sub-Riemannian $k$-step Carnot group of homogeneous dimension $Q$. In this paper, we shall prove several geometric inequalities concerning smooth hypersurfaces (i.e. codimension one submanifolds) immersed in $\GG$, endowed with the $\HH$-perimeter measure.

An alternative treatment modality for cellulite: LPG endermologie

Background: LPG endermologie is a worldwide FDA-approved massage system used in the treatment of cellulite. Objective: The aim of this study is to evaluate safety, efficacy, and the slimming potential of LPG endermologie. Material and methods: A total of 118 women (mean age, 34.59 ± 8.02 years) were enrolled in this study. The LPG treatment sessions were performed twice weekly and continued for at least 15 sessions. The outcome was clinically evaluated using digital photography for cellulite grade assessment while perimetric measurements for eight body sites were performed. The evaluation also included measurements of body weight and body fat percentage (BFP). Results: One hundred and seventeen patients (99%) showed loss in body circumference measurements. A mean body circumference reduction of 2.9 ± 1.6 cm was obtained per site for all patients. There was a mean body circumference loss which was statically significant with p < 0.001. Weight loss was detected in one hundred and three patients (87%). The mean body weight loss was 2.717 ± 1.938 kg for all patients. One hundred and ten subjects (93%) also showed decreases in BFP. The questionnaire indicated high satisfaction in 81 (69%) patients. Conclusion: LPG endermologie is a well-tolerated and effective alternative treatment modality for slimming and body contouring.

Teat perimeters for South African Boer and Nguni goats: Use of these measurements to predict milk production potential and kids growth

The aim of this trial was to assess the possibility of using teat perimeter in estimating milk production potential and kids’ growth rate in Nguni and Boer goats of South Africa. Traditionally, the productive capacity of goats doe, are judged to a large extent by the physical phenotypic characteristics. In this trial a 2 × 2 factorial design (two goat breeds and two nutritional management systems) were used. Thirty six (36) recently kidded does (18 Boer goats and 18 Nguni goats) were also used in this experiment. The investigation was conducted between seven (7) and hundred (100) days post-partum. Half (n = 9) the Boer goat does and half (n = 9) the Nguni does were allocated randomly within breed to an extensive (veld) feeding treatment, and the other half per breed to an intensive (high energy) feeding treatment (this is traditionally practiced by profit driven intensive farmers). The results revealed that teat perimeter measurement could be used in both breeds under an intensive feeding regime. The results further revealed that in the extensive feeding regime, the prediction of milk potential through teat perimeter can only be carried out in the Nguni goat breed. These results indicate that the teat perimeter measurement can be used to measure milk production of the Nguni goats based on the two feeding systems. These results appear to suggest that teat perimeters in the Nguni goat could be the best tool for the resource poor farmers. Key words: Milk production, teat, perimeter, Boer goat, Nguni goat.

Bioimpedance for Oedema Evaluation after Total Knee Arthroplasty

Electrical bioimpedance spectroscopy (BIS) allows the evaluation of limb extracellular fluid (R0) and total fluid (Rinf). BIS could facilitate post-surgical oedema evaluation after total knee arthroplasty (TKA), as it is easily performed and is non-invasive. However, neither its applicability in this context nor the influence of metallic implants on measurement has been evaluated. The aim of this study was to evaluate the influence of TKA implants on the BIS R0 and Rinf variables used for oedema evaluation. This was a prospective non-randomized comparative clinical trial. One oedema-free group of patients with TKA was compared with a group presenting similar characteristics except for the arthroplasty, to assess the influence of the implant on BIS measurement in the absence of oedema. The TKA group included 15 patients who had undergone surgery more than a year previously, and the control group included 19 patients awaiting TKA surgery. Volume and perimeter measurements served as reference criterions. The lower limb percentage differences for BIS, knee perimeter and volume were calculated. The significance of differences between groups was calculated for all measurement methods, using the Mann-Whitney test. The setting was a Department of Orthopedic Surgery and Traumatology in a university hospital. The differences between groups were not significant for R0, Rinf, volume and perimeter. R0 showed the smallest mean difference in limb percentage difference between groups [means (SD): TKA 3.98 (8.09), controls 3.97 (5.16)]. The lower-leg percentage difference in the TKA group is comparable with that of healthy subjects. R0 can be used for oedema evaluation following TKA surgery, as there was no sign of alteration from the metallic implant. These findings indicate the potential for early oedema evaluation after TKA. More research is warranted to extensively validate the application of BIS for oedema evaluation after TKA.

After six months of anti-psychotic treatment: Is the improvement in mental health at the expense of physical health?

IntroductionMorbidity and mortality due to cardiovascular causes in patients with schizophrenia are higher than in the general population, a fact that has been observed more since second generation anti-psychotics came into general use. ObjectivesTo determine the incidence of metabolic syndrome in patients with a previously untreated first psychotic episode, as well as the prospective changes in the parameters that define the criteria of metabolic syndrome. MethodAn observational study with a prospective cohort design including patients who were admitted to the Acute Unit of Donostia Hospital. ResultsA total of 21 patients were included in the study, of which 19 completed it. Just over one-quarter (26.3%) of the patients developed a metabolic syndrome at six months. Statistically significant differences were observed in the following parameters: (1) abdominal perimeter measurement with an increase of 14.6cm at six months (P=.001); (2) triglyceride levels with a mean increase over the initial measurement of 48.99mg/dl (P=.039); and (3) fasting blood glucose levels with a mean increase of 10.72mg/dl (P=.001). ConclusionsSignificant changes were observed in metabolic parameters in a short period with the subsequent risk of associated cardiovascular events in a group of young patients. Actions are required to be directed at ensuring appropriate monitoring of these patients in order to measures to minimise the risks.

Crioterapia com e sem bandagem úmida na adiposidade localizada de mulheres jovens

Introdução: A adiposidade localizada ocorre por mudanças na distribuição do tecido adiposo e anormalidades metabólicas. Objetivos: Verificar o efeito da técnica de crioterapia à base de gel canforado e mentol utilizada isoladamente e com bandagem úmida, na adiposidade localizada de mulheres jovens. Métodos: Foram selecionadas 33 mulheres jovens com adiposidades localizadas. As voluntárias foram randomizadas em três grupos: gel sem bandagem úmida (GG=11), gel com bandagem úmida (GGB=11) e gel placebo (GGP=11). Foram realizados anamnese, exame físico, avaliação da composição e da imagem corporal. Resultados: Observou-se que apenas o GG obteve diminuição estatisticamente significante na perimetria de coxa distal. Conclusões: A técnica de crioterapia à base de gel canforado e mentol, utilizada isoladamente, foi eficaz na diminuição da perimetria de coxa distal apenas, e com bandagem úmida não alterou a adiposidade localizada de mulheres jovens.

Comparison of digital image analysis using elliptic Fourier descriptors and major dimensions to phenotype seed shape in hexaploid wheat (Triticum aestivum L.)

Digital image analysis (DIA) is widely used for describing plant organ shape. However, the various types of shape descriptors that can be generated using DIA may identify different loci in genetic analyses. The purpose of this study was to evaluate two different DIA approaches to quantifying wheat seed shape for exploring trait correlations and quantitative trait loci (QTL) mapping. Phenotypic data were produced using the software programs ImageJ (National Institutes of Health, USA, http://rsbweb.nih.gov/ij/ ) and SHAPE (Hiroyoshi Iwata, http://lbm.ab.a.u-tokyo.ac.jp/≃iwata/shape/ ). ImageJ generates measures of length, width, perimeter, and area that can be used to describe dimensions of objects, whereas SHAPE generates elliptic Fourier descriptors (EFDs) to capture shape variation such as roughness, asymmetric skewing, or other two-dimensional aspects not encompassed by axes or distinctions in overall object area. There were significant differences in the results of the QTL analysis depending on the DIA software used. The use of EFDs to characterize horizontal measures of seed shape in wheat identified more QTL with higher LOD scores than length to width ratio. Additionally, the entire three dimensional shape of the seed described using two images in different orientations was shown to identify seed shape QTL that co-located with flour yield (FLYLD) and would go undetected based solely on a two dimensional image of the seed. Both methods identified QTL for length, width, thickness, and vertical perimeter that were co-localized with QTL for FLYLD.

Factors Predicting the Rate of Functional Progression in Early and Suspected Glaucoma

Clinical trials in glaucoma have often sought to predict whether a patient will progress or remain stable. This study proposes to combine and support results from earlier studies, forming a model to predict the actual rate of functional change in glaucoma. Data were taken from 259 eyes of 150 participants with early or suspected glaucoma in the ongoing Portland Progression Project. A total of 3854 study visits were available, each consisting of visual acuity, confocal scanning laser ophthalmoscopy (CSLO), and perimetry. The rate of functional change was calculated over each of 1541 series of six consecutive visits. Mixed effects models were formed to predict these rates using baseline perimetric measurements and CSLO parameters, together with IOP, age, and change in visual acuity through the series (to remove any confound from media changes). Cup volume from CSLO was predictive of subsequent rate of functional change (P = 0.036), together with baseline mean deviation (P < 0.001) and pattern standard deviation (P = 0.097), age (P = 0.013), maximum IOP during the sequence (P = 0.004), and change in acuity during the sequence (P = 0.022). In a similar model, rim area was less predictive of functional change (P = 0.066). A larger optic cup and/or a more damaged visual field are predictive of more rapid perimetric sensitivity loss. The structural parameters most closely correlated with current functional status may not be the parameters that are most useful for predicting the future course of a patient's disease. Maximum IOP may be a more important risk factor than mean IOP over the same time period.

Tras 6 meses de tratamiento antipsicótico: ¿mejoría de la salud mental a costa de la salud física?

The morbidity and mortality due to cardiovascular causes in patients with schizophrenia is higher than in the general population, a fact that has been observed more since second generation anti-psychotics came into general use. To determine the incidence of metabolic syndrome in patients with a previously untreated first psychotic episode, as well as the prospective changes in the parameters that define the criteria of metabolic syndrome. An observational study with a prospective cohort design including patients who were admitted to the Acute Unit of Donostia Hospital. A total of 21 patients were included in the study, of which 19 completed it. Just over one-quarter (26.3%) of the patients developed a metabolic syndrome at six months. Statistically significant differences were observed in the following parameters: 1) abdominal perimeter measurement with an increase of 14.6 cm at six months (P=.001); 2) triglyceride levels with a mean increase over the initial measurement of 48.99 mg/dl (P=.039); and 3) fasting blood glucose levels with a mean increase of 10.72 mg/dl (P=.001). Significant changes were observed in metabolic parameters in a short period with the subsequent risk of associated cardiovascular events in a group of young patients. Actions are required directed at ensuring appropriate monitoring of these patients in order to measures to minimise the risks.

EVALUACIÓN DE INDICADORES BIOMÉTRICOS EN LLAMAS (Lama glama) DE LAS VARIEDADES CH’ACCU Y K’ARA.

Ninety nine llamas K´aras and Ch´accus with their babies were selected at La Raya Research and Production Center of Altiplano National University, Puno, to evaluate the measures of thoracic perimeter (PT), thigh volume (VM) and rump area (ASG) in baby llamas as biometric indicators for body weight (PV) by multiple regression models, and correlations between these variables with udder size (length and width) of the mothers. These evaluations were done at 1st, 2nd and 3rd month of age. The calculations of VM and ASG were done through geometric figures of truncated cone and trapezium respectively, using the Autocad engineering software. The coefficients of determination increased from medium to high as baby llamas increased in age, and the highest value was found at the age of 7 (R2 = 76.3%) and 3 (R2 = 70.0%) for Ch´accus and K´aras respectively. The major effect came from PT in Ch´acus whereas in K´aras was from PT and ASG at 1st and 3rd month of age and VM at 7th month (p&lt;0.05). The relationship in baby llamas between PV and biometric measurements were high, positive and significant, especially at 7 months of age. The relationships between udder size (length and width) and PV, ASG, VM and PT were low with the exception of K´aras at 7 months of age. In general, PV, VM, ASG and PT increased by 55, 53, 34 and 19% and 108, 90, 60 and 35% at 3 and 7 months of age respectively, and without significant differences between breeds. Changes in udder size from the 1st month of age until 3 and 7 months of age were minimum. The results suggested that PT, VM and ASG could be used as biometric indicators of PV in selecting llamas for meat production.

Anatomy of corpus callosum in prenatally malnourished rats

The effect of prenatal malnutrition on the anatomy of the corpus callosum was assessed in adult rats (45-52 days old). In the prenatally malnourished animals we observed a significant reduction of the corpus callosum total area, partial areas, and perimeter, as compared with normal animals. In addition, the splenium of corpus callosum (posterior fifth) showed a significant decrease of fiber diameters in the myelinated fibers without changing density. There was also a significant decrease in diameter and a significant increase in density of unmyelinated fibers. Measurements of perimeter's fractal dimensions from sagittal sections of the brain and corpus callosum did not show significant differences between malnourished and control animals. These findings indicate that cortico-cortical connections are vulnerable to the prenatal malnutrition, and suggest this may affect interhemispheric conduction velocity, particularly in visual connections (splenium).

SURFACE RUPTURE OF THE NORMAL SEISMIC FAULTS AND SLOPE FAILURES APPEARED IN APRIL 11&lt;sup&gt;th&lt;/sup&gt;, 2011 FUKUSHIMA-PREFECTURE HAMADOORI EARTHQUAKE

On April 11th, 2011, Iwaki region of Fukushima prefecture was jolted by Fukushima-Prefecture Hamadoori Earthquake. Surface ruptures were observed along causative Idosawa and Yunotake normal faults. In addition to numerous small slope failures, a coherent landslide and building structures of Tabito Junior High School, bisected by Idosawa Fault, were found along the causative faults. A precise digital elevation model of the coherent landslide was obtained through the ground and air-born LiDAR surveys. The measurements of perimeters of the gymnasium building and the swimming pool of Tabito Junior High School have shown that ground undergoes a slow and steady/continual deformation.

Perimeter of sublevel sets in infinite dimensional spaces

Abstract. We compare the perimeter measure with the Airault–Malliavin surface measure and we prove that all open convex subsets of abstract Wiener spaces have finite perimeter. By an explicit counter-example, we show that in general this is not true for compact convex domains.

Vermian Biometric Parameters in the Normal and Abnormal Fetal Posterior Fossa

The purposes of this study were to describe a 3-dimensional sonographic technique for evaluation of the fetal vermis and to compare vermian biometric parameters in fetuses with a normal and an abnormal posterior fossa. A prospective study was conducted from 2006 through 2008 on 12 fetuses with an abnormal posterior fossa and 73 healthy control fetuses from 18 to 35 weeks' gestation. Three-dimensional scans of the fetal head were performed in the axial plane, using static volume contrast imaging in the C-plane. The vermian perimeter, cross-sectional area, and superoinferior diameter were measured and compared between abnormal and normal fetuses using the Wilcoxon nonparametric test. Linear regression analysis was used to describe trends of the vermis during gestation. The z scores for perimeter, cross-sectional area, and superoinferior diameter measurements in the abnormal posterior fossa group in each 2-week interval were calculated. Twelve fetuses with an abnormal posterior fossa were recruited: 3 with a Blake pouch cyst, 1 vermian cyst, 1 enlarged cisterna magna, 2 Dandy-Walker malformation, 4 partial vermian agenesis, and 1 hemicerebellar hypoplasia. The vermian cross-sectional area was reduced significantly in the fetuses with an abnormal posterior fossa compared with the control fetuses starting at 18 to 19 weeks' gestation (P = .01); the mean vermian superoinferior diameter was lower only from 22 to 23 weeks (P = .01); and the mean vermian perimeter was decreased from 28-29 weeks' gestation (P = .03). Linear regression analysis of the parameters showed that fetuses with an abnormal posterior fossa had a statistically significantly lower growth rate than control fetuses during gestation (P < .001). Measurements of the cross-sectional area were more useful than those of the perimeter and superoinferior diameter in distinguishing between fetuses with a normal and an abnormal posterior fossa during the early stages of gestation.