Estimation of breast prosthesis volume by the Cavalieri principle using magnetic resonance images

Imaging of the Silicone Implant with a 3D SPACE MR Sequence: The Accuracy for Estimating Implant Volume and Reconstructing Implant Deformation in Breast Surgery

OBJECTIVE

The study is to assess the accuracy and reliability of 3D simulated magnetic resonance imaging with SPACE sequence for estimating implant volume and reconstructing implant deformation, which may assist in the diagnosis of implant complications and making individualized surgical plans for these patients.

METHODS

MRI examinations of ten silicone implants were performed with T2, H₂O-excitation SPACE sequence (T2-spc-H₂O) and silicone-excitation SPACE sequence (T2-spc-Silicone) to find the most accurate method to estimate implant volume by ITK-SNAP. The effect of implant deformation and voxel size of silicone-excitation SPACE sequence on volume measurement was investigated. Thirteen normal patients and ten patients with implant complications (Wuhan Tongji Hospital from March 2017 to May 2019) were enrolled for testing the accuracy and reliability of 3D simulated MRI with silicone-excitation SPACE sequences for volume measurement and reconstructing implant deformation in patients.

RESULTS

The absolute volume differences of T2-spc-Silicone group were significantly less than T2-spc-H₂O and T2 group (6.28 vs. 23.27 vs. 42.19 mL, P < 0.05) in vitro. No significant difference was found between the normality group and the deformation group for estimating the volume of implants. Besides, the voxel size of T2-spc-Silicone from 0.5 × 0.5 × 0.5 mm to 5.0 × 5.0 × 5.0 mm did not significantly affect the accuracy of volume measurement of the implants in deformation state. However, 3D images of the implant became blurred with the voxel size increased. With the voxel size larger than 1.5 × 1.5 × 1.5 mm, the scores of image quality decreased significantly. The number of folds could not be identified accurately with the voxel size larger than 2.0 × 2.0 × 2.0 mm. In normal patients, the measurement errors of T2-spc-Silicone were around 10 mL. In the patients with implant complications, there was no significant difference between measured volume and the actual volume of implants. Moreover, implant deformations were clearly presented by T2-spc-Silicone with the voxel size of 1.0 × 1.0 × 1.0 mm. The results showed excellent intraobserver reliability (ICC = 0.997 > 0.8), and internal consistency ranged from 0.986 to 0.997 (P < 0.001).

CONCLUSIONS

The method to measure implant volume by 3D simulated magnetic resonance imaging with T2-spc-Silicone sequence had possessed desirable accuracy and reliability. The deformation of the implant and the voxel size of the T2-spc-Silicone sequence didn't exhibit a significant effect on the accuracy of the measurement. T2-spc-Silicone with voxel size less than 2.0 × 2.0 × 2.0 mm could be used for 3D reconstruction of the implant deformation. The 1.0 × 1.0 × 1.0 mm was a suitable voxel size to reconstruct implant deformation clearly and quickly.

LEVEL OF EVIDENCE IV

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Breast Asymmetry, Classification, and Algorithm of Treatment: Our Experience

BACKGROUND

In the literature, several classifications of breast asymmetries and treatment protocols have been proposed over time, which are mainly based on etiological or morphological characteristics of the deformity. The aim of this study was to present our new classification, based on patient's self-consciousness of breast asymmetry, a simple and reliable treatment algorithm is also presented.

METHODS

The case series included 343 patients treated between January 2006 and January 2015. Only patients presenting with developmental breast asymmetries were included in the study. All patients underwent prior classification in three groups based on the patient's degree of awareness of their asymmetry. A specific treatment algorithm was associated with each group according to breast size, grade of ptosis, and patient's desire. At the 48-month follow-up appointment, patients completed an anonymous questionnaire that addressed satisfaction with breast shape, size, and symmetry, scar appearance, body perception, self-esteem, perceived attractiveness, intimate life, and overall feelings about their breasts.

RESULTS

Mean patient age was 24.6 years (range 18-57 years). Mean follow-up was 54.4 months (6 months to 9 years). At the 48-month follow-up, 66.7% of the patients completed a visual analog scale (VAS) satisfaction questionnaire. An overall satisfaction rate of 77.0% was reported, and a statistically significant difference in the distribution of the overall satisfaction between groups was found. No patient expressed complete dissatisfaction.

CONCLUSIONS

The proposed classification and the surgical algorithm is a simple, applicable, and reliable method to assess and treat breast asymmetries with a high satisfaction rate as confirmed from our results.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266.

Therapeutic time window of anti-high mobility group box-1 antibody administration in mouse model of spinal cord injury

Spinal cord injury (SCI) is a devastating neurologic disorder that often leads to permanent disability, and there is no effective treatment for it. High mobility group box-1 (HMGB1) is a damage-associated molecular protein that triggers sterile inflammation upon injuries. We have previously shown that two administrations of neutralizing monoclonal antibody (mAb) against HMGB1 (immediately after (0 h) and 6 h after) SCI dramatically improves functional recovery after SCI in mice. However, when considering clinical application, 0 h after SCI is not practical. Therefore, in this study, we examined the therapeutic time window of the mAb administration. Injection at 3 h after SCI significantly improved the functional recovery comparably to injection immediately after SCI, while injection at 6 h was less effective, and injection at 9 or 12 h had no therapeutic effect. We also found beneficial effects of injection at 3 h after injury on blood-spinal cord barrier maintenance, inflammatory-related gene expression and preservation of the damaged spinal cord tissue. Taken together, our results suggest that a single administration of anti-HMGB1 mAb within a proper time window could be a novel and potential therapeutic strategy for SCI.

Prior Treatment with Anti-High Mobility Group Box-1 Antibody Boosts Human Neural Stem Cell Transplantation-Mediated Functional Recovery After Spinal Cord Injury

Together with residual host neurons, transplanted neural stem cell (NSC)-derived neurons play a critical role in reconstructing disrupted neural circuits after spinal cord injury (SCI). Since a large number of tracts are disrupted and the majority of host neurons die around the lesion site as the damage spreads, minimizing this spreading and preserving the lesion site are important for attaining further improvements in reconstruction. High mobility group box-1 (HMGB1) is a damage-associated molecular pattern protein that triggers sterile inflammation after tissue injury. In the ischemic and injured brain, neutralization of HMGB1 with a specific antibody reportedly stabilizes the blood-brain barrier, suppresses inflammatory cytokine expression, and improves functional recovery. Using a SCI model mouse, we here developed a combinatorial treatment for SCI: administering anti-HMGB1 antibody prior to transplantation of NSCs derived from human induced pluripotent stem cells (hiPSC-NSCs) yielded a dramatic improvement in locomotion recovery after SCI. Even anti-HMGB1 antibody treatment alone alleviated blood-spinal cord barrier disruption and edema formation, and increased the number of neurites from spared axons and the survival of host neurons, resulting in functional recovery. However, this recovery was greatly enhanced by the subsequent hiPSC-NSC transplantation, reaching an extent that has never before been reported. We also found that this improved recovery was directly associated with connections established between surviving host neurons and transplant-derived neurons. Taken together, our results highlight combinatorial treatment with anti-HMGB1 antibody and hiPSC-NSC transplantation as a promising novel therapy for SCI. Stem Cells 2018;36:737-750.

The Age-Related Development of Maxillary Sinus in Children

INTRODUCTION

Paranasal sinuses are complex structures and show individual variation. Providing normative values for paranasal sinus size and their changes related to age could be helpful in evaluating the presence of some diseases related to sinonasal region. The purpose of the current study was to investigate the development of maxillary sinuses and evaluate the volume changes according to age and sex by using stereological and ellipsoidal formula methods after that to compare these approaches with each other in children.

MATERIALS AND METHODS

This retrospective volumetric computed tomography (CT) study was carried out on 361 individuals (180 females, 181 males) between 0 and 18 years old (10 females, 10 males in each group, only 14 age group includes 11 males) with no signs of sinus pathology volumetric estimations determined on CT images using point-counting approach of stereological methods and ellipsoid formula by using morphometric data.

RESULTS

Maxillary sinus volume measurements that were obtained using 2 methods were increased with age in both sexes until 16 years old. There was a significant correlation determined between 2 methods (ICC 0.894-1.000 for right and 0.862-0.999 for left maxillary sinus measurements). According to the sex, the right and left mean maxillary sinuses volumes were determined at 8.30 ± 5.19 and 8.57 ± 5.53 cm(3) in male and at 7.60 ± 4.57 and 7.99 ± 4.73 cm(3) in female by using ellipsoid formula respectively. By the stereological method these values were 8.28 ± 5.26, 8.44 ± 5.35 cm(3) and 7.64 ± 4.55, 7.85 ± 4.73 cm(3) respectively. There was no statistically significant difference between the volume of maxillary sinuses with sex and side using both methods.

CONCLUSIONS

This study presents the basic data for studies relative to the development of the maxillary sinus in children according to 2 methods. The current study demonstrated that the point-counting method and ellipsoid formula are both effective in determining volume estimation of maxillary sinuses and are well suited for CT studies.

Objective breast volume, shape and surface area assessment: a systematic review of breast measurement methods

BACKGROUND

There are many methods of measuring the breast and their clinical applications are well described in the literature. However, there has been no attempt to compare these various methods to allow the user to have a broad overview of the subject. The authors have attempted to summarise all the available methods to measure the breast in this article to provide a useful reference for all.

METHODS

A comprehensive literature search of PubMed was performed, and the resulting articles were screened and reviewed. The data regarding the methods' mechanism, reliability, time and cost were evaluated and compared.

RESULTS

A total of 74 articles dating from 1970 to 2013 were included in this study. All of the methods can be classified into those that measure (1) volume, (2) shape and (3) surface area. Each category consists of several methods that work through different mechanisms and they vary in their reliability and feasibility. Based on their mechanism, the volume measurement methods were further grouped into the natural shape methods, the stereological method, the geometrical methods and the mathematical modelling method.

CONCLUSIONS

More objective breast evaluation can be achieved if all three dimensions (volume, shape and surface area) are considered. In the volume measurements, 3D modelling and the MRI are the most reliable tools. Linear measurement (geometry) and mathematical modelling are less accurate but are more economical. In the shape measurements, besides the traditional linear measurement, 3D methods that can deliver colour-coded maps and Swanson's 2D photographic measurement system are capable of depicting and tracking breast shape changes after surgery. Although the surface area metric has not been used extensively, it has potential in clinical and research applications.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

A stereological study on the correlation of inferior turbinate hypertrophy and paranasal sinus disease

The objective of this study is to investigate the correlation between inferior turbinate size and paranasal sinus opacification on computerized tomography (CT) scans. Paranasal sinus CT scans of a total of 185 patients (92 males, 93 females) were examined in terms of sinus opacification. Sizes of the inferior turbinates were measured using stereological method and these sizes in normal and opacified paranasal sinuses are compared using one-way analysis of variance. Scans of 185 patients (93 female, 92 male) aged between 12 and 84 (mean 37.85 ± 16.27) years were examined in this study. Sizes of the inferior turbinates were found to be increased significantly in case of opacification of ipsilateral maxillary and anterior ethmoid sinuses (p = 0.000 and p = 0.4, respectively) on both sides. On the other hand, such a relationship could not be demonstrated for sizes of inferior turbinates with opacified or non-opacified posterior ethmoid, frontal and sphenoid sinuses. In conclusion, the combination of CT and the Cavalieri principle can provide an unbiased, direct, and assumption-free estimate of the regions of interest. The presented method can be efficiently applied without any need for special software, additional equipment, or personnel than that required for routine CT in daily use. Paranasal sinus disease, especially the inflammatory diseases of maxillary and anterior ethmoid sinuses, must be carefully investigated in cases with inferior turbinate hypertrophy.

Volumetric measurement of polyacrylamide hydrogel injected for breast augmentation using magnetic resonance imaging

Volumetric measurement of polyacrylamide hydrogel (PAHG) is useful for surgical planning. It is not only a significant factor in the preoperative evaluation of breast augmentation, but may also directly affect the postoperative shape of the breast. The objective of the present study was to evaluate whether magnetic resonance imaging (MRI) is able to provide precise calculations of injected PAHG volumes. MRI scans of ten randomly selected patients were imported to Mimics software. The volumes of PAHG were obtained following the reconstruction of the injected PAHG. In order to assess the precision and observer independency of the technique, the volumes of PAHG were estimated by three plastic surgeons using this method. No significant differences were identified among the PAHG injection volumes calculated by the three observers (P=0.173). The intra-observer correlation coefficient was 0.964, which indicates the precision and feasibility of this method for calculating the volume of PAHG. The use of MRI in combination with Mimics software to calculate PAHG volumes is likely to be of significant clinical benefit in preoperative surgical planning.

A new evaluation method for the intracranial volume changes and subdural effusion of patients following endoscopic third ventriculostomy

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is a procedure commonly applied in the treatment of non-communicating (obstructive) hydrocephalus. One of the rare complications that can occur following ETV is a subdural effusion, even though this procedure is considered to be a more controlled and natural method of cerebrospinal fluid drainage compared to external drainage. In this study, we evaluated the intracranial volume changes and subdural effusion of patients following ETV using Cavalieri method.

METHOD

Volumes analysis of the cranial cavity, brain, ventricles and subdural effusions of two patients after ETV were performed on computed tomography images using the Cavalieri principle, one of the stereological methods.

RESULTS

The preoperative total intracranial volumes and the preoperative brain volumes decreased for both patients during the postoperative 3rd, 10th and 30th days. Following ETV, the volumes of the lateral ventricles of both patients initially decreased during the postoperative 3rd and 10th days, however, the volumes returned almost to their preoperative size by the end of the 30th day. The effusions were seen on the postoperative 3rd and 10th days resolved by the end of the 30th day.

CONCLUSION

Our results show that the Cavalieri method can be used to unbiased prediction of intracranial volume changes and to follow the subdural effusion after the ETV surgery.

Antitumor effect of sFlt-1 gene therapy system mediated by Bifidobacterium Infantis on Lewis lung cancer in mice

Soluble fms-like tyrosine kinase receptor (sFlt-1) is a soluble form of extramembrane part of vascular endothelial growth factor receptor-1 (VEGFR-1) that has antitumor effects. Bifidobacterium Infantis is a kind of non-pathogenic and anaerobic bacteria that may have specific targeting property of hypoxic environment inside of solid tumors. The aim of this study was to construct Bifidobacterium Infantis-mediated sFlt-1 gene transferring system and investigate its antitumor effect on Lewis lung cancer (LLC) in mice. Our results demonstrated that the Bifidobacterium Infantis-mediated sFlt-1 gene transferring system was constructed successfully and the system could express sFlt-1 at the levels of gene and protein. This system could not only significantly inhibit growth of human umbilical vein endothelial cells induced by VEGF in vitro, but also inhibit the tumor growth and prolong survival time of LLC C57BL/6 mice safely. These data suggest that Bifidobacterium Infantis-mediated sFlt-1 gene transferring system presents a promising therapeutic approach for the treatment of cancer.

Magnetic resonance images and linear measurements in the surgical treatment of breast asymmetry

BACKGROUND

Objective evaluation of breast asymmetry surgical treatment should consider not only breast shape but also breast volume.

METHODS

For this study, 22 patients with primary breast asymmetry were evaluated by magnetic resonance imaging (MRI) as well as linear measurements preoperatively and 6 months postoperatively. The mean difference between the pre- and postoperative linear measurements was graduated from excellent to poor. Breast volume was estimated by MRI from axial reconstruction for three-dimensional application using the Cavalieri formula and specific software.

RESULTS

A strong correlation (r = 0.817) was found between the pre- and postoperative breast volumes, as increased or decreased by the surgical procedure. Patients with less postoperative volume differences tended to have the best ratings with linear measurements. When the same surgical procedure was performed bilaterally or when only one breast was treated by surgery, greater volume symmetry was observed.

CONCLUSIONS

Linear measurements and MRI are objective methods for evaluating postoperative symmetry, and when used in association, can help plastic surgeons to achieve favorable results in mammary asymmetry treatment.

[Breast volume assessment based on 3D surface geometry: verification of the method using MR imaging]

Differences in breast volume and contour are subjectively estimated by surgeons. 3D surface imaging using 3D scanners provides objective breast volume quantification, but precision and accuracy of the method requires verification. Breast volumes of five test individuals were assessed using a 3D surface scanner. Magnetic resonance imaging (MRI) reference volumes were obtained to verify and compare the 3D scan measurements. The anatomical thorax wall curvature was segmented using MRI data and compared to the interpolated curvature of the posterior breast volume delimitation of 3D scan data. MRI showed higher measurement precision, mean deviation (expressed as percentage of volume) of 1.10+/-0.34% compared to 1.63+/-0.53% for the 3D scanner. Mean MRI [right (left) breasts: 638 (629)+/-143 (138) cc] and 3D scan [right (left) breasts: 493 (497)+/-112 (116) cc] breast volumes significantly correlated [right (left) breasts: r=0.982 (0.977), p=0.003 (0.004)]. The posterior thorax wall of the 3D scan model showed high agreement with the MRI thorax wall curvature [mean positive (negative) deviation: 0.33 (-0.17)+/-0.37 cm]. High correspondence and correlation of 3D scan data with MRI-based verifications support 3D surface imaging as sufficiently precise and accurate for breast volume measurements.

Comparison of four methods for the estimation of intracranial volume: a gold standard study

Investigators can infer how much reduction in volume has occurred since brain volume was at its peak, by combining measures of brain volume with measures of intracranial volume (ICV). Several methodologies have been proposed to asses the ICV. However, we have not seen a gold-standard study evaluating the results of the methodologies for the assessment of ICV. In the present study, the actual intracranial volume of 20 dry skulls was measured using the water-filling method, using this as a gold standard. Anthropometry, cephalometry, point-counting, and planimetry techniques were applied to the same skulls to estimate the ICV. Anthropometric and cephalometric measurements were carried out directly on skulls and roentgenograms, respectively. Consecutive computed tomography sections at a thickness of 10 mm were used to estimate the ICV of the skulls by means of the point-counting and planimetry methods. The mean (+/-SD) of the actual ICV measured by the water-filling method was 1,262.0 +/- 160.4 cm(3) (1,389.5 +/- 96.5 cm(3) for males and 1,134.5 +/- 94.3 cm(3) for females, respectively). Our results showed that the estimated values obtained by all four methods differed from the actual volumes of the skulls (P < 0.05). The data obtained by anthropometry resulted in overestimation. However, cephalometry, point-counting, and planimetry methods produced underestimation. After calibration, there were no significant differences between the actual volumes and the results of the four methods (P > 0.05). While the anthropometric method is easy and quick to apply, its result may deviate from the actual values. The optimized stereological techniques of point-counting and planimetry methods may provide unbiased ICV results since they take the third dimension of the structures into account.

Stereological evaluation of liver volume in living donor liver transplantation using MDCT via the Cavalieri method

In living donor liver transplantation (LDLT), obtaining the precise volume of the graft is very important to decrease volume-related postoperative complications, especially in cases with suspected small-for size grafts. We used stereology based on the Cavalieri method (CM), a new method to measure liver graft volume, and compared the results with those obtained through intraoperative measurement (IOM) and through multidetector computed tomography (MDCT) measurement. Liver volumes estimated using the 3 methods were well-correlated with each other (r(2) = 0.94 and P < 0.001 for IOM and CM; r(2) = 0.91 and P < 0.001 for IOM and MDCT, and r(2) = 0.95 and P < 0.001 for CM and MDCT); however, they were different from each other (in descending order, 908 +/- 124 cm(2), 861 +/- 121 cm(2), and 777 +/- 168 cm(2) for MDCT, CM, and IOM, respectively). Although MDCT and CM overestimated the volumes, the results of CM were almost similar to those obtained via IOM. In conclusion, our results suggest that CM measured the liver graft volume more reliably. Thus, its use, particularly in cases with suspected small-for-size graft, may prove useful.

Comparison of Three Methods for the Estimation of Total Intracranial Volume

There is a well-known close relationship between the total intracranial volume (TIV) and the brain size. Several studies in different countries have estimated the cranial capacity, which indirectly reflects the brain volume. However, we have not seen a study evaluating the results of the methodologies for the assessment of TIV. This study was carried out on 30 normal subjects whose ages ranged between 19 and 77 years old (males, 18; females, 12). Three different methods were used to assess the TIV. The mean (+/-SD) estimated TIV using linear dimensions method in males and females were 1416.8 +/- 64 cm and 1291.9 +/- 152 cm, respectively. The mean estimated TIV using point counting method in males and females was 1474 +/- 93 cm and 1252 +/- 72 cm, respectively. By using the planimetric method of the mean and SD of TIV, male and females were 1492.1 +/- 74 cm and 1319.6 +/- 100 cm, respectively. There were no statistical difference between TIV measurements obtained using the optimized stereologic technique and planimetry (P > 0.05). TIV between males and females was statistically significant (P < 0.001). This study showed that there are minor differences among the given 3 distinct methods. With the disadvantage of requiring more time to apply, the planimetry and point counting methods provide more assumption-free results than the anthropometric approach. However, the anthropometric method can be applied to assess TIV without needing sophisticated tools.

Stereological evaluation of treatment response in patients with non-resectable hepatic alveolar echinococcosis using computed tomography via the Cavalieri method

INTRODUCTION

The purposes of this study were to describe and adapt the relevant methods of computed tomography (CT) and stereology to estimate parasitic volume in the liver, to compare the efficiency of benzimidazole treatment in hepatic alveolar echinococcosis (AE), and to determine whether the response rates measured by the stereological method are correlated with those measured by simple volumetric measurements (SVM).

METHODS

Nine eligible patients with non-resectable AE were included in the study. By using their abdominal CT at the baseline and after a year of treatment, treatment responses of the cases were evaluated both by the stereological method via a software and by SVM, retrospectively. The volume estimation was performed in our study using a different approach that consisted of three separate stages combined with the Cavalieri method of modern design stereology.

RESULTS

The response rates were -17 +/- 55% and -12 +/- 37% by the Cavalieri method and SVM, respectively; however, they were not statistically significant (P = 0.59 and 0.21 for the Cavalieri method and SVM, respectively). Although some cases had comparable results, others had different response rates, and the two methods showed no significant correlation (r = -0.31, P = 0.41).

CONCLUSIONS

Because this modified method provides accurate results by reducing margin of errors, even in case of bizarre shape of AE, a correct, unbiased, and reliable management of the cases with AE via this method may be possible. Owing to lack of a correlation with SVM, it is suggested that a measurement via SVM may be wrong and its use in the evaluation of the treatment response in such cases will not be sufficient and completely true.

Volumetric evaluation of the paranasal sinuses in normal subjects using computer tomography images: a stereological study

OBJECTIVE

The size and shape of paranasal sinuses are especially relevant when considering endoscopic sinus surgery. For this reason, the size of the paranasal sinuses has been the subject of many studies, none of which has used stereological methods to estimate the volume. In the present stereological study, we estimated the volume of paranasal sinuses of normal males and females.

MATERIAL AND METHODS

We used a combination of the Cavalieri principle and computer tomography scans taken from 39 male and 38 female patients to estimate the volumes of frontal, maxillary, ethmoidal and sphenoidal sinuses.

RESULTS

The mean volumes of frontal, maxillary, ethmoidal and sphenoidal sinuses were estimated bilaterally, producing mean volumes of 11.6+/-0.8, 35.9+/-1.3, 11.8+/-0.4 and 13.6+/-0.7 cm(3), respectively. When the correlations between estimated volumes were analyzed statistically a positive relation was found for the paranasal sinuses. The size of the sinuses tends to decrease with age.

CONCLUSION

The findings of the present study using the stereological methods could provide data for the evaluation of normal and pathological volumes of the paranasal sinuses.

The effects of section thickness on the estimation of liver volume by the Cavalieri principle using computed tomography images

Estimation of liver volume using routine CT scans has been described previously. We have, however, not found a gold standard study which analyzes the effect of section thickness on the estimation of liver volume using CT images. In the present study, five normal livers obtained from cadavers were scanned using a Spiral CT Scanner (Xpress/GX Toshiba, Tocigi-Ken) in the horizontal plane. Consecutive sections at a thickness of 10, 5 and 1mm were used to estimate the total volume of the livers by means of the Cavalieri principle. With a view to evaluating inter-observer differences, liver volume was estimated by three observers. The estimated volume using the classical volume estimation formula did not concur with the actual volume of the livers obtained by the fluid displacement technique. The section thickness has an over- or under-projection effect on the estimated volume. The obtained volume estimation results were, therefore, calibrated using three different approaches. The volume obtained by the calibration formulae did not differ statistically from actual liver volumes (P<0.05). There were also no significant differences between the performers' estimates (P>0.05). Results showed that the effect of section thickness on the volume estimates could not be omitted and the obtained values could be calibrated using the proposed approaches presented in this study.

Assessment of the optimum section thickness for the estimation of liver volume using magnetic resonance images: a stereological gold standard study

Estimation of liver volume using magnetic resonance (MR) images has been described previously. We have, however, not found a gold standard study, which analyzes the effect of section thickness on the estimation of liver volume. In the present study, five normal cadaveric livers were scanned in the horizontal plane using a 1.5 T MR machine (Signa 1.5T SYS#GEMSOW General Electronic, Wisconsin, USA). Consecutive sections at a thickness of 10, 7.5, 5 and 2.5 mm were used to estimate the total volume of the livers by means of the Cavalieri principle. The point counting and planimetry were used for the volume estimates. With a view to evaluating the accuracy of two techniques, all the estimations were done by the same observer. The estimated volumes concur with the actual volume of the livers obtained by the fluid displacement technique (p > 0.05). However, the section thickness has an over- or under-projection effect on the estimated volume. The obtained volume estimation results were analyzed to reveal the deviation principles of the estimates based on the section thickness. The most suitable section thickness for the liver volume estimation was assessed to be 4-5 mm. There were no significant differences between the estimation results of two methods (p > 0.05). The point-counting technique did, however, take less time than planimetry for estimating liver volume from MR images. Results also showed that the effect of section thickness on volume estimates using the two approaches could not be omitted and the values obtained could be calibrated using the proposed regression formula presented in this study.

Unbiased estimation of tumor regression rates during chemoradiotherapy for esophageal carcinoma using CT and stereology

SUMMARY. The purpose of the present study is to estimate tumor volumes of 10 patients with esophageal carcinoma on serial CT images that are obtained before and after chemoradiotherapy using a stereological method. In this study, tumor volume was measured using the Cavalieri method of modern design stereology with a combination of three separate stages. Firstly, detailed systematic series of axial CT images of 1-cm thickness were obtained throughout the whole tumor area of each subject and to magnify them all CT images were projected on a screen by overhead projector and then were marked by manually tracing the outline of areas with tumor on serial CT images that are projected onto the screen. Secondly these images were drawn on paper. Finally the images on paper were evaluated with a point-counting method. It was shown in a pilot study analyzed that 100 test points counted on about 6--8 serial slices through for esophagus wall, lumen and wall + lumen are sufficient to secure coefficient of error (CE) on the estimates of volumes as in this study. It was found that tumor volumes before and after radiotherapy for esophagus wall, lumen and wall + lumen was 10.34 cm(3), 1.15 cm(3) and 11.75 cm(3) before and 5.93 cm(3), 1.43 cm(3) and 7.65 cm(3) after radiotherapy, respectively. When only esophagus wall and lumen volumes or wall + lumen volumes before and after radiotherapy were statistically compared, the difference between either esophagus wall (P<0.01) and lumen (P<0.01) volumes or total volumes (P<.1) were significant. It is concluded that CT estimated tumor volumes may be helpful in both evaluating the clinical situation of patients and providing a simple index to assess the efficiency of therapy, prediction of tumor regression rate and minimizing the risk of chemoradiotherapy damage.