Measurement of breast volume: comparison of techniques

A system of graduated disks has been previously described as a method to determine breast volume. The accuracy and limitations of this system have not previously been reported. Comparison of these disks with a standardized volumetric method shows this simple system to be accurate. Standard linear correlation analysis was good for the entire group of breasts measured (r = 0.718). Conversion to true volume M is represented by the least-square line M = 20.33 + 1.37G. The correlation is expected to fail at volumes greater than 425 cc (greater than the calibration on the largest Grossman disk). Elimination of volumes greater than 425 cc, however, produced no improvement in correlation coefficient. Firm breasts (i.e., capsular contractures) displace less uniformly into the conical restraint of the disk and cause an overestimation of their volume. Three breasts in this series were evaluated with Baker grade III and IV capsular contractures. Elimination of these values improved the correlation between the two volume analyses (r = 0.853 and M = 1.56G - 4.48). We suggest that when confronted with very large or firm breasts that volumes determined by the Grossman disk be interpreted with care. A formula for calculation of the true breast volume from the Grossman measurement has been derived and presented.     

Impaired left ventricular filling due to right-to-left ventricular interaction in patients with pulmonary arterial hypertension

The aim of this study was to investigate the contribution of direct right-to-left ventricular interaction to left ventricular filling and stroke volume in 46 patients with pulmonary arterial hypertension (PAH) and 18 control subjects. Stroke volume, right and left ventricular volumes, left ventricular filling rate, and interventricular septum curvature were measured by magnetic resonance imaging and left atrial filling by transesophageal echocardiography. Stroke volume, left ventricular end-diastolic volume, and left ventricular peak filling rate were decreased in PAH patients compared with control subjects: 28 +/- 13 vs. 41 +/- 10 ml/m(2) (P < 0.001), 46 +/- 14 vs. 61 +/- 14 ml/m(2) (P < 0.001), and 216 +/- 90 vs. 541 +/- 248 ml/s (P < 0.001), respectively. Among PAH patients, stroke volume did not correlate to right ventricular end-diastolic volume or mean pulmonary arterial pressure but did correlate to left ventricular end-diastolic volume (r = 0.62, P < 0.001). Leftward interventricular septum curvature was correlated to left ventricular filling rate (r = 0.64, P < 0.001) and left ventricular end-diastolic volume (r = 0.65, P < 0.001). In contrast, left atrial filling was normal and not correlated to left ventricular end-diastolic volume. In PAH patients, ventricular interaction mediated by the interventricular septum impairs left ventricular filling, contributing to decreased stroke volume.     

A biomechanical model of mammographic compressions

A number of biomechanical models have been proposed to improve nonrigid registration techniques for multimodal breast image alignment. A deformable breast model may also be useful for overcoming difficulties in interpreting 2D X-ray projections (mammograms) of 3D volumes (breast tissues). If a deformable model could accurately predict the shape changes that breasts undergo during mammography, then the model could serve to localize suspicious masses (visible in mammograms) in the unloaded state, or in any other deformed state required for further investigations (such as biopsy or other medical imaging modalities). In this paper, we present a validation study that was conducted in order to develop a biomechanical model based on the well-established theory of continuum mechanics (finite elasticity theory with contact mechanics) and demonstrate its use for this application. Experimental studies using gel phantoms were conducted to test the accuracy in predicting mammographic-like deformations. The material properties of the gel phantom were estimated using a nonlinear optimization process, which minimized the errors between the experimental and the model-predicted surface data by adjusting the parameter associated with the neo-Hookean constitutive relation. Two compressions (the equivalent of cranio-caudal and medio-lateral mammograms) were performed on the phantom, and the corresponding deformations were recorded using a MRI scanner. Finite element simulations were performed to mimic the experiments using the estimated material properties with appropriate boundary conditions. The simulation results matched the experimental recordings of the deformed phantom, with a sub-millimeter root-mean-square error for each compression state. Having now validated our finite element model of breast compression, the next stage is to apply the model to clinical images.     

Anatomical and functional assessment of brown adipose tissue by magnetic resonance imaging

Brown adipose tissue (BAT) is the primary tissue responsible for nonshivering thermogenesis in mammals. The amount of BAT and its level of activation help regulate the utilization of excessive calories for thermogenesis as opposed to storage in white adipose tissue (WAT) which would lead to weight gain. Over the past several years, BAT activity in vivo has been primarily assessed by positron emission tomography-computed tomography (PET-CT) scan using 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) to measure glucose utilization associated with BAT mitochondrial respiration. In this study, we demonstrate the feasibility of mapping and estimating BAT volume and metabolic function in vivo in rats at a 9.4T magnetic resonance imaging (MRI) scanner using sequences available from clinical MR scanners. Based on the morphological characteristics of BAT, we measured the volume distribution of BAT with MRI sequences that have strong fat-water contrast. We also investigated BAT volume by utilizing spin-echo MRI sequences. The in vivo MRI-estimated BAT volumes were correlated with direct measurement of BAT mass from dissected samples. Using MRI, we also were able to map hemodynamic responses to changes in BAT metabolism induced pharmacologically by β3-adrenergic receptor agonist, CL-316,243 and compare this to BAT activity in response to CL-316,243 assessed by PET 18F-FDG. In conclusion, we demonstrate the feasibility of measuring BAT volume and function in vivo using routine MRI sequences. The MRI measurement of BAT volume is consistent with quantitative measurement of the tissue ex vivo.     

Hippocampal Volume Reduction in Congenital Central Hypoventilation Syndrome

Children with congenital central hypoventilation syndrome (CCHS), a genetic disorder characterized by diminished drive to breathe during sleep and impaired CO₂ sensitivity, show brain structural and functional changes on magnetic resonance imaging (MRI) scans, with impaired responses in specific hippocampal regions, suggesting localized injury.We assessed total volume and regional variation in hippocampal surface morphology to identify areas affected in the syndrome. We studied 18 CCHS (mean age±std: 15.1±2.2 years; 8 female) and 32 healthy control (age 15.2±2.4 years; 14 female) children, and traced hippocampi on 1 mm³ resolution T1-weighted scans, collected with a 3.0 Tesla MRI scanner. Regional hippocampal volume variations, adjusted for cranial volume, were compared between groups based on t-tests of surface distances to the structure midline, with correction for multiple comparisons. Significant tissue losses emerged in CCHS patients on the left side, with a trend for loss on the right; however, most areas affected on the left also showed equivalent right-sided volume reductions. Reduced regional volumes appeared in the left rostral hippocampus, bilateral areas in mid and mid-to-caudal regions, and a dorsal-caudal region, adjacent to the fimbria.The volume losses may result from hypoxic exposure following hypoventilation during sleep-disordered breathing, or from developmental or vascular consequences of genetic mutations in the syndrome. The sites of change overlap regions of abnormal functional responses to respiratory and autonomic challenges. Affected hippocampal areas have roles associated with memory, mood, and indirectly, autonomic regulation; impairments in these behavioral and physiological functions appear in CCHS.     

A Functional Magnetic Resonance Imaging (fMRI) Study of Cue-Induced Smoking Craving in Virtual Environments

Smokers who are exposed to smoking-related cues show cardiovascular reactivity and smoking craving compared with their responses to neutral cues, and increased cue reactivity predicts decreased likelihood of successful cessation. Several brain imaging studies suggested four candidate brain regions that might differ in gray matter volumes and densities between smokers and nonsmokers. However, in these studies, smokers were only exposed to smoking-related objects. In our pilot study utilizing a virtual reality (VR) technique, virtual environments (VEs) were more immersive and evoked smoking craving more effectively than traditionally used methods. In this study, we sought to test whether smokers could experience cue-induced smoking craving inside the MRI scanner by using the VR system. The smoking cue reactivity scenario was based in part on our preliminary task and consisted of 2D and 3D (or VE) conditions. The group mean of participants had increased activity in the prefrontal cortex (PFC), left anterior cingulate gyrus (ACC), left supplementary motor area, left uncus, right inferior temporal gyrus, right lingual gyrus, and right precuneus in the 2D condition. Areas of differential activation in the 3D condition were as follows: left superior temporal gyrus, right superior frontal gyrus, and left inferior occipital gyrus in the 3D condition. This finding is consistent with those of previous studies of nicotine craving showing PFC and ACC activation. However, in the 3D condition, the PFC including the superior frontal gyrus as well as the superior temporal gyrus, inferior occipital gyrus, and cerebellum were activated. Therefore, in the 3D condition, participants seemed to have more attention, visual balance, and coordinating movement than in the 2D condition.     

Breast volume and anthropomorphic measurements: normal values

Fifty-five consecutive female volunteers were evaluated. Linear measurements of the breast and nipple position were determined to fixed points on the chest wall. Volume determination was done by a standard chest-wall casting technique. A highly significant difference was found between left and right breasts in the axilla-to-nipple distance and nipple-to-midline measurements. A significant difference was also found in the distance from the lowest point of the breast (patient upright) to the nipple. Analysis of the volumetric difference between right and left breasts did not achieve statistical significance.     

Breast volume measurement of 248 women using biostereometric analysis

A study of volumes of the right and left breasts of 248 subjects was undertaken using biostereometric analysis. This measurement technique uses close-range stereophotogrammetry to characterize the shape of the breast and is noncontact, noninvasive, accurate, and rapid with respect to the subject involvement time. Volumes and volumetric differences between breast pairs were compared, using chi-square tests, with handedness, perception of breast size by each subject, age, and menstrual status. No significant relationship was found between the handedness of the subject and the larger breast volume. Several groups of subjects based on age and menstrual status were accurate in their perception of breast size difference. Analysis did not confirm the generally accepted clinical impression of left breast volume dominance. Although a size difference in breast pairs was documented, neither breast predominated.     

An anatomic basis for fetal right ventricular dominance and arterial pressure sensitivity

Fetal right ventricular dominance of flow and arterial pressure sensitivity were recently recognized but controversial findings. We investigated ventricular volumes, weights and dimensions in order to understand if there were anatomic differences between the ventricles which might explain these differential functional findings in the fetal sheep. Forty-four near term lambs and their hearts were weighed. Right and left ventricular free wall weights were not different. Volumes were measured by generating in vitro pressure-volume relations and by casting the two ventricles after fixation at equal, physiologic pressures. Right ventricular volume was greater than left ventricular volume by both techniques. Ventricular interaction and a restraining effect of the pericardium were present. Measurements of the fixed ventricles and their casts revealed the following: left ventricular wall thickness was slightly greater than right ventricular wall thickness; lateral ventricular diameters were not different but anteroposterior ventricular diameters were much greater in the right than left ventricle. Because of these findings, the right ventricular circumferential radii of curvature were greater than for the left ventricle as was the radius to wall thickness ratio. Greater right ventricular volume and radius to wall thickness ratio may be important factors in right ventricular flow dominance and greater sensitivity to arterial pressure.     

Renal volume and human somatic type

The abdominal C. T. of 128 patients (45 women and 83 men) aged more than 25, without any history of renal disease, have been analyzed by an evaluation computer. By the measure of the areas of kidney in each C. T. scan, the volume of the whole organ has been calculated. In men the volume resulted to be cm3 167 +/- 84,6 (M. +/- S.D.) for the right kidney and cm3 170 +/- 58 for the left one. In women it was cm3 142 +/- 54,9 for the right kidney and cm3 156 +/- 54,5 for the left one. The volumes of the organs collected into 3 classes according to their dimension, have been compared to the 3 somatic types of the subjects (Mega, Medium, Micro) obtained following the Brian & coll. method. Using a test for a monotonic trend for two ordered variables, no significant association has been demonstrated between the volume of the kidney and the human somatic type.     

Continuous monitoring of right ventricular volume changes using a conductance catheter in the rabbit.

To assess the reliability of conductance (G) catheter for evaluating right ventricular (RV) volume changes, a miniature (3.5F) six-electrode catheter was developed and tested in 11 New Zealand rabbit hearts. In five animals the heart was excised; in six it was left in the thorax. RV conductance was recorded while the RV was filled with blood in 0.25-ml steps at different left ventricular (LV) volumes. Linear correlation of measured conductance vs. reference volumes was computed. RV conductance was highly correlated with reference volume [correlation coefficient (r) ranging from 0.991 to 0.999]. Slope of regression lines was not significantly affected by LV volume variations in 1-ml steps or by acute conductance changes of structures surrounding the heart, whereas the intercept was affected only by the 0- to 1-ml LV volume change. In four rabbits, RV conductance changes during a cardiac cycle [stroke volume- (SV) G] were compared in vivo with electromagnetic flow probe-derived estimates of SV (SVem) as stroke volume was varied by graded inferior vena caval occlusion. SV-G correlated well with SVem (r ranging from 0.92 to 0.96). This correlation persisted after the thorax was filled with saline; however, significant differences were found in individual slopes (P < 0.001). These results show that the conductance catheter has a potential to reliably monitor in vivo relative RV volume changes in small-animal hearts.     

Relation between trunk fat volume and reduction of total lung capacity in obese men

Reduction in total lung capacity (TLC) in obese men is associated with restricted expansion of the thoracic cavity at full inflation. We hypothesized that thoracic expansion was reduced by the load imposed by increased total trunk fat volume or its distribution. Using MRI, we measured internal and subcutaneous trunk fat and total abdominal and thoracic volumes at full inflation in 14 obese men [mean age: 52.4 yr, body mass index (BMI): 38.8 (range: 36-44) kg/m(2)] and 7 control men [mean age: 50.1 yr, BMI: 25.0 (range: 22-27.5) kg/m(2)]. TLC was measured by multibreath helium dilution and was restricted (<80% of the predicted value) in six obese men (the OR subgroup). All measurements were made with subjects in the supine position. Mean total trunk fat volume was 16.65 (range: 12.6-21.8) liters in obese men and 6.98 (range: 3.0-10.8) liters in control men. Anthropometry and mean total trunk fat volumes were similar in OR men and obese men without restriction (the ON subgroup). Mean total intraabdominal volume was 9.41 liters in OR men and 11.15 liters in ON men. In obese men, reduced thoracic expansion at full inflation and restriction of TLC were not inversely related to a large volume of 1) intra-abdominal or total abdominal fat, 2) subcutaneous fat volume around the thorax, or 3) total trunk fat volume. In addition, trunk fat volumes in obese men were not inversely related to gas volume or estimated intrathoracic volume at supine functional residual capacity. In conclusion, this study failed to support the hypotheses that restriction of TLC or impaired expansion of the thorax at full inflation in middle-aged obese men was simply a consequence of a large abdominal volume or total trunk fat volume or its distribution.     

Influence of Head Motion on the Accuracy of 3D Reconstruction with Cone-Beam CT: Landmark Identification Errors in Maxillofacial Surface Model

PurposeThe purpose of this study was to investigate the influence of head motion on the accuracy of three-dimensional (3D) reconstruction with cone-beam computed tomography (CBCT) scan.ResultsRendered surface models with head motion were similar to the control model in appearance; however, the landmark identification errors showed larger values in models with head motion than in the control. In particular, the Porion in the horizontal rotation models presented statistically significant differences (P < .05). Statistically significant difference in the errors between the right and left side landmark was present in the left side rotation which was opposite direction to the scanner rotation (P < .05).ConclusionsPatient movement during CBCT scan might cause landmark identification errors on the 3D surface model in relation to the direction of the scanner rotation. Clinicians should take this into consideration to prevent patient movement during CBCT scan, particularly horizontal movement.     

Hippocampal and Left Subcallosal Anterior Cingulate Atrophy in Psychotic Depression

Background

Psychotic depression is arguably the most diagnostically stable subtype of major depressive disorder, and an attractive target of study in a famously heterogeneous mental illness. Previous imaging studies have identified abnormal volumes of the hippocampus, amygdala, and subcallosal region of the anterior cingulate cortex (scACC) in psychotic depression, though studies have not yet examined the role of family history of depression in these relationships.

Methods

20 participants with psychotic depression preparing to undergo electroconvulsive therapy and 20 healthy comparison participants (13 women and 7 men in each group) underwent structural brain imaging in a 1.5 T MRI scanner. 15 of the psychotic depression group had a first-degree relative with diagnosed affective disorders, while the healthy control group had no first-degree relatives with affective disorders. Depression severity was assessed with the Hamilton Depression Rating Scale and duration of illness was assessed in all patients. Automated neural nets were used to isolate the hippocampi and amygdalae in each scan, and an established manual method was used to parcellate the anterior cingulate cortex into dorsal, rostral, subcallosal, and subgenual regions. The volumes of these regions were compared between groups. Effects of laterality and family history of affective disorders were examined as well.

Results

Patients with psychotic depression had significantly smaller left scACC and bilateral hippocampal volumes, while no group differences in other anterior cingulate cortex subregions or amygdala volumes were present. Hippocampal atrophy was found in all patients with psychotic depression, but reduced left scACC volume was found only in the patients with a family history of depression.

Conclusions

Patients with psychotic depression showed significant reduction in hippocampal volume bilaterally, perhaps due to high cortisol states associated with this illness. Reduced left scACC volume may be a vulnerability factor related to family history of depression.     

Quantification of Regional Breast Density in Four Quadrants Using 3D MRI—A Pilot Study

PURPOSE: This study presented a three-dimensional magnetic resonance (MR)–based method to separate a breast into four quadrants for quantitative measurements of the quadrant breast volume (BV) and density. METHODS: Breast MR images from 58 healthy women were studied. The breast and the fibroglandular tissue were segmented by using a computer-based algorithm. A breast was divided into four quadrants using two perpendicular planes intersecting at the nipple or the nipple-centroid line. After the separation, the BV, the fibroglandular tissue volume, and the percent density (PD) were calculated. The symmetry of the quadrant BV in the left and right breasts separated by using the nipple alone, or the nipple-centroid line, was compared. RESULTS: The quadrant separation made on the basis of the nipple-centroid line showed closer BVs in four quadrants than using the nipple alone. The correlation and agreement for the BV in corresponding quadrants of the left and the right breasts were improved after the nipple-centroid reorientation. Among the four quadrants, PD was the highest in the lower outer and the lowest in the upper outer (significant than the other three) quadrants (P < .05). CONCLUSIONS: We presented a quantitative method to divide a breast into four quadrants. The reorientation based on the nipple-centroid line improved the left to right quadrant symmetry, and this may provide a better standardized method to measure quantitative quadrant density. The cancer occurrence rates are known to vary in different sites of a breast, and our method may provide a tool for investigating its association with the quantitative breast density.     

Assessment of right and left ventricular function in healthy mice by blood-pool pinhole gated SPECT

The feasibility of blood-pool pinhole ECG gated SPECT was investigated in healthy mice to assess right and left ventricular function analysis. Anaesthetized (isoflurane 1-1.5%) adult CD1 mice (n=11) were analyzed after intravenous administration of 0.2 ml of 550 MBq of (99m)Tc human albumin. For blood-pool gated SPECT imaging, 48 ventral step and shoot projections with eight time bins per RR over 180 degrees with 64x64 word images were acquired with a small animal gamma camera equipped with a pinhole collimator of 12 cm in focal length and 1.5 mm in diameter. For appropriate segmentation of right and left ventricular volumes, a 4D Fourier analysis was performed after reconstruction and reorientation of blood-pool images with a voxel size of 0.55x0.55x0.55 mm(3). Average right and left ejection fractions were respectively 52+/-4.7% and 65+/-5.2%. Right end diastolic and end systolic volumes were significantly higher compared with the corresponding left ventricular volumes (P<0.0001 each). A linear correlation between right and left stroke volumes (r=0.9, P<0.0001) was obtained and right and left cardiac outputs were not significantly different 14.2+/-1.9 and 14.1+/-2 ml/min, respectively. To cite this article: C. Goetz et al., C. R. Biologies 331 (2008).     

三种正常大鼠磁共振成像心功能基础数据采集和分析

目的大鼠是常用的制备心脏病模型的实验动物,而磁共振成像（MRI）技术已经成为评价心脏病模型病理进程和药效的重要技术手段,但是目前国内外没有正常大鼠心脏的磁共振成像技术参数,影响了这一技术的应用。本文利用磁共振成像技术,采集和定量分析Wistar、Sprague-Dawley和Lewis三种常用大鼠的左、右心室功能参数,为心脏病模型制备和分析提供参考数据。方法利用7．0T高场强MRI心脏电影（CINE）序列,分析这三种常用大鼠活体心脏组织的左、右心室心功能参数。结果获得三种大鼠左、右心室的8—9周龄功能参数,包括：左、右心室的舒张末容积（EDV）、收缩末容积（ESV）、射血分数（EF）;左心室乳头肌层面舒张末期内径（EDD）、收缩末期内径（ESD）、短轴缩短率（Fs）、舒张末前后室壁厚度（EDAWT,EDPWT）、收缩末前后室壁厚度（ESAWT,ESPWT）、前室壁增厚率（AWT）和后室壁增厚率（PwT）;右心室乳头肌层面舒张末室壁厚度（EDWT）、收缩末室壁厚度（ESWT）和室壁增厚率（WT）等十八项心脏主要功能和结构的正常值。结论本研究获得的三种大鼠十八项心脏主要功能和结构的正常值,可作为心脏病模型制备成模判定和病理进程、药物评价的参考数据。     

Maternal Smoking during Pregnancy and Fetal Organ Growth: A Magnetic Resonance Imaging Study

Objective

To study whether maternal cigarette smoking during pregnancy is associated with alterations in the growth of fetal lungs, kidneys, liver, brain, and placenta.

Design

A case-control study, with operators performing the image analysis blinded.

Setting

Study performed on a research-dedicated magnetic resonance imaging (MRI) scanner (1.5 T) with participants recruited from a large teaching hospital in the United Kingdom.

Participants

A total of 26 pregnant women (13 current smokers, 13 non smokers) were recruited; 18 women (10 current smokers, 8 nonsmokers) returned for the second scan later in their pregnancy.

Methods

Each fetus was scanned with MRI at 22–27 weeks and 33–38 weeks gestational age (GA).

Main outcome measures

Images obtained with MRI were used to measure volumes of the fetal brain, kidneys, lungs, liver and overall fetal size, as well as placental volumes.

Results

Exposed fetuses showed lower brain volumes, kidney volumes, and total fetal volumes, with this effect being greater at visit 2 than at visit 1 for brain and kidney volumes, and greater at visit 1 than at visit 2 for total fetal volume. Exposed fetuses also demonstrated lower lung volume and placental volume, and this effect was similar at both visits. No difference was found between the exposed and nonexposed fetuses with regards to liver volume.

Conclusion

Magnetic resonance imaging has been used to show that maternal smoking is associated with reduced growth of fetal brain, lung and kidney; this effect persists even when the volumes are corrected for maternal education, gestational age, and fetal sex. As expected, the fetuses exposed to maternal smoking are smaller in size. Similarly, placental volumes are smaller in smoking versus nonsmoking pregnant women.     

Analysis of right ventricular function in healthy mice and a murine model of heart failure by in vivo MRI

Because of its complex geometry, assessment of right ventricular (RV) function is more difficult than it is for the left ventricle (LV). Because gene-targeted mouse models of cardiomyopathy may involve remodeling of the right heart, the purpose of this study was to develop high-resolution functional magnetic resonance imaging (MRI) for in vivo quantification of RV volumes and global function in mice. Thirty-three mice of various age were studied under isoflurane anesthesia by electrocardiogram-triggered cine-MRI at 7 T. MRI revealed close correlations between RV and LV stroke volume and cardiac output (r = 0.97, P < 0.0001 each). Consistent with human physiology, murine RV end-diastolic and end-systolic volumes were significantly higher compared with LV volumes (P < 0.05 each). MRI in mice with LV heart failure due to myocardial infarction revealed significant structural and functional changes of the RV, indicating RV dysfunction. Hence, MRI allows for the quantification of RV volumes and global systolic function with high accuracy and bears the potential to evaluate mechanisms of RV remodeling in mouse models of heart failure.     

Validation of in vivo assessment of facial soft-tissue volume changes and clinical application in midfacial distraction: a technical report

The purpose of this study was to validate the assessment of visible volume changes of the facial soft tissue with an optical three-dimensional sensor and to introduce new parameters for the evaluation of the soft-tissue shape achieved from three-dimensional data of selected cases of midfacial distraction. Images of a truncated cone of known volume were assessed repeatedly with an optical three-dimensional sensor based on phase-measuring triangulation to calculate the volume. Two cubic centimeters of anesthetic solution was injected into the right malar region of 10 volunteers who gave their informed consent. Three-dimensional images were assessed before and immediately after the injections for the assessment of the visible volume change. In five patients who underwent midfacial distraction after a high quadrangular Le Fort I osteotomy, three-dimensional scans were acquired before and 6 and 24 months after the operation. The visible soft-tissue volume change in the malar-midfacial area and the mean distance of the accommodation vector that transformed the preoperative into the postoperative surface were calculated. The volume of the truncated cone was 235.26 +/- 1.01 cc, revealing a measurement uncertainty of 0.4 percent. The injections of anesthetic solution into the malar area resulted in an average visible volume change of 2.06 +/- 0.06 cc. The measurement uncertainty was 3 percent. In the five patients, the average distance of maxillary advancement was 6.7 +/- 2.3 mm after 6 months and 5.4 +/- 3.0 mm after 2 years. It was accompanied by a mean visible volume increase of 8.92 +/- 5.95 cc on the right side and 9.54 +/- 4.39 cc on the left side after 6 months and 3.54 +/- 3.70 cc and 4.80 +/- 3.47 cc, respectively, after 2 years. The mean distance of the accommodation vector was 4.41 +/- 1.94 mm on the right side and 4.74 +/- 1.32 mm on the left side after 6 months and 1.62 +/- 1.96 mm and 2.16 +/- 1.52 mm, respectively, after 2 years. The assessment of visible volume changes by optical three-dimensional images can be carried out with considerable accuracy. The determination of volume changes and accompanying accommodation vectors completes the cephalometric analysis during the follow-up of patients undergoing midfacial distraction. The new parameters will help to assess normative soft-tissue data on the basis of three-dimensional imaging with a view to an improved three-dimensional prediction of the operative outcome of orthognathic surgery.