Influence Of Slice Thickness Research Articles

The Influence of Slice Thickness, Sharpness, and Contrast Adjustments on Inferior Alveolar Canal Segmentation on Cone-Beam Computed Tomography Scans: A Retrospective Study.

This retrospective study aims to investigate the impact of cone-beam computed tomography (CBCT) viewing parameters such as contrast, slice thickness, and sharpness on the identification of the inferior alveolar nerve (IAC). A total of 25 CBCT scans, resulting in 50 IACs, were assessed by two investigators using a three-score system (good, average, and poor) on cross-sectional images. Slice thicknesses of 0.25 mm, 0.5 mm, and 1 mm were tested, along with varying sharpness (0, 6, 8, and 10) and contrast (0, 400, 800, and 1200) settings. The results were statistically analyzed to determine the optimal slice thickness for improved visibility of IAC, followed by evaluating the influence of sharpness and contrast using the optimal thickness. The identified parameters were then validated by performing semi-automated segmentation of the IACs and structure overlapping to evaluate the mean distance. Inter-rater and intra-rater reliability were assessed using Kappa statistics, and inferential statistics used Pearson's Chi-square test. Inter-rater and intra-rater reliability for all parameters were significant, ranging from 69% to 83%. A slice thickness of 0.25 mm showed consistently "good" visibility (80%). Sharpness values of zero and contrast values of 1200 also demonstrated high frequencies of "good" visibility. Overlap analysis resulted in an average mean distance of 0.295 mm and a standard deviation of 0.307 mm across all patients' sides. The study revealed that a slice thickness of 0.25 mm, zero sharpness value, and higher contrast value of 1200 improved the visibility and accuracy of IAC segmentation in CBCT scans. The individual patient's characteristics, such as anatomical variations, decreased bone density, and absence of canal walls cortication, should be considered when using these parameters.

Validation of a Length-Adjusted Abdominal Arterial Calcium Score Method for Contrast-Enhanced CT Scans.

The Agatston score on noncontrast computed tomography (CT) scans is the gold standard for calcium load determination. However, contrast-enhanced CT is commonly used for patients with atherosclerotic cardiovascular diseases (ASCVDs), such as peripheral arterial occlusive disease (PAOD) and abdominal aortic aneurysm (AAA). Currently, there is no validated method to determine calcium load in the aorta and peripheral arteries with a contrast-enhanced CT. This study validated a length-adjusted calcium score (LACS) method for contrast-enhanced CT scans. The LACS (calcium volume in mm3/arterial length in cm) in the abdominal aorta was calculated using four-phase liver CT scans of 30 patients treated between 2017 and 2021 at the University Medical Center Groningen (UMCG) with no aortic disease. Noncontrast CT scans were segmented with a 130 Hounsfield units (HU) threshold, and a patient-specific threshold was used for contrast-enhanced CTs. The LACS was calculated and compared from both segmentations. Secondly, the interobserver variability and the influence of slice thickness (0.75 mm vs. 2.0 mm) was determined. There was a high correlation between the LACS from contrast-enhanced CT scans and the LACS of noncontrast CTs (R2 = 0.98). A correction factor of 1.9 was established to convert the LACS derived from contrast-enhanced CT to noncontrast CT scans. LACS interobserver agreement on contrast-enhanced CT was excellent (1.0, 95% confidence interval = 1.0-1.0). The 0.75 mm CT threshold was 541 (459-625) HU compared with 500 (419-568) HU on 2 mm CTs (p = 0.15). LACS calculated with both thresholds was not significantly different (p = 0.63). The LACS seems to be a robust method for scoring calcium load on contrast-enhanced CT scans in arterial segments with various lengths.

Automated subcortical volume estimation from 2D MRI in epilepsy and implications for clinical trials

PurposeMost techniques used for automatic segmentation of subcortical brain regions are developed for three-dimensional (3D) MR images. MRIs obtained in non-specialist hospitals may be non-isotropic and two-dimensional (2D). Automatic segmentation of 2D images may be challenging and represents a lost opportunity to perform quantitative image analysis. We determine the performance of a modified subcortical segmentation technique applied to 2D images in patients with idiopathic generalised epilepsy (IGE).MethodsVolume estimates were derived from 2D (0.4 × 0.4 × 3 mm) and 3D (1 × 1x1mm) T1-weighted acquisitions in 31 patients with IGE and 39 healthy controls. 2D image segmentation was performed using a modified FSL FIRST (FMRIB Integrated Registration and Segmentation Tool) pipeline requiring additional image reorientation, cropping, interpolation and brain extraction prior to conventional FIRST segmentation. Consistency between segmentations was assessed using Dice coefficients and volumes across both approaches were compared between patients and controls. The influence of slice thickness on consistency was further assessed using 2D images with slice thickness increased to 6 mm.ResultsAll average Dice coefficients showed excellent agreement between 2 and 3D images across subcortical structures (0.86–0.96). Most 2D volumes were consistently slightly lower compared to 3D volumes. 2D images with increased slice thickness showed lower agreement with 3D images with lower Dice coefficients (0.55–0.83). Significant volume reduction of the left and right thalamus and putamen was observed in patients relative to controls across 2D and 3D images.ConclusionAutomated subcortical volume estimation of 2D images with a resolution of 0.4 × 0.4x3mm using a modified FIRST pipeline is consistent with volumes derived from 3D images, although this consistency decreases with an increased slice thickness. Thalamic and putamen atrophy has previously been reported in patients with IGE. Automated subcortical volume estimation from 2D images is feasible and most reliable at using in-plane acquisitions greater than 1 mm x 1 mm and provides an opportunity to perform quantitative image analysis studies in clinical trials.

CT-based radiomics for preoperative prediction of early recurrent hepatocellular carcinoma: technical reproducibility of acquisition and scanners.

To test the technical reproducibility of acquisition and scanners of CT image-based radiomics model for early recurrent hepatocellular carcinoma (HCC). We included primary HCC patient undergone curative therapies, using early recurrence as endpoint. Four datasets were constructed: 109 images from hospital #1 for training (set 1: 1-mm image slice thickness), 47 images from hospital #1 for internal validation (sets 2 and 3: 1-mm and 10-mm image slice thicknesses, respectively), and 47 images from hospital #2 for external validation (set 4: vastly different from training dataset). A radiomics model was constructed. Radiomics technical reproducibility was measured by overfitting and calibration deviation in external validation dataset. The influence of slice thickness on reproducibility was evaluated in two internal validation datasets. Compared with set 1, the model in set 2 indicated favorable prediction efficiency (the area under the curve 0.79 vs. 0.80, P = 0.47) and good calibration (unreliability statistic U: P = 0.33). However, in set 4, significant overfitting (0.63 vs. 0.80, P < 0.01) and calibration deviation (U: P < 0.01) were observed. Similar poor performance was also observed in set 3 (0.56 vs. 0.80, P = 0.02; U: P < 0.01). CT-based radiomics has poor reproducibility between centers. Image heterogeneity, such as slice thickness, can be a significant influencing factor.

Influence of slice thickness on result of CT histogram analysis in indeterminate adrenal masses

PurposeThe aim was to determine the optimal slice thickness of CT images and the optimal threshold of negative voxels for CT histogram analysis to distinguish adrenal adenomas from non-adenomas with a mean attenuation more than 10 Hounsfield units (HU).MethodsVolume CT histogram analysis of 83 lipid-poor adenomas and 80 non-adenomas was performed retrospectively. The volume of interest was extracted from each adrenal lesion, and the mean attenuation, standard deviation (SD), and percentage of voxels with a negative CT value were recorded using reconstructions with different slice thicknesses (5 mm, 2.5 mm, 1.25 mm). The percentage of negative voxels was correlated with SD as a measure of image noise and with the reference splenic tissue values. The sensitivity, specificity, and positive predictive value (PPV) for the identification of adenomas were calculated using reconstructions with different slice thicknesses and three different thresholds of negative voxels (1%, 5%, 10%).ResultsThe percentage of negative voxels increased with a thinner slice thickness and correlated with increasing CT image noise in adenomas, non-adenomas, and spleen. Using a threshold of 10% negative voxels and a slice thickness of 5 mm, we reached a sensitivity of 53.0%, specificity of 98.8% and the highest PPV, and thus we propose this combination for clinical use. Other combinations achieved a clearly lower specificity and PPV as a result of the increasing noise in CT images.ConclusionThe CT slice thickness significantly affects the result and diagnostic value of histogram analysis. Thin CT slice reconstructions are inappropriate for histogram analysis.

Effect of Microwave Blanching on Slice Thickness and Quality Analysis of Star Fruit

Star fruit (Averrhoa carambola L.) is one of the underutilized tropical fruits and is a good source of vitamins and minerals. Peroxidase (POD) is the most heat stable enzyme which is used as an indicator for adequacy of blanching process. Blanching is a prerequisite for the preservation of fruits and vegetables. Hot water blanching is having disadvantages like wastewater production and loss of valuable nutrients by leaching. Microwave blanching is one of the emerging and clean technology which seems to provide a better nutrient retention due to shorter heating time and zero wastewater production. Therefore, the present investigation was carried out to identify a suitable blanching method (hot water blanching and microwave blanching) for different slice thickness (5, 10 and 15 mm) of star fruit that ensures enzyme inactivation and maximum retention of therapeutic value (ascorbic acid and oxalic acid). It was observed that blanching at 600, 480, 240 and 120 W power level for a slice thickness of 5, 10 and 15 mm required blanching time of 30-60 s, 40-70 s, 60-80 s, 80-150 s and 300-720 s respectively. For a given slice thickness, the moisture content of samples decreased with increase in power level. The moisture content was reduced to 84-88% w.b. from an initial value of 90% w.b. depending on power level and blanching time combinations. At the same time, the oxalic acid decreased significantly with increase in slice thickness and a decrease in power level. The change in ascorbic acid also showed a similar trend but the influence of slice thickness was not significant (p&gt;0.05).

Influence of gray level discretization on radiomic feature stability for different CT scanners, tube currents and slice thicknesses: a comprehensive phantom study

Background: Radiomic analyses of CT images provide prognostic information that can potentially be used for personalized treatment. However, heterogeneity of acquisition- and reconstruction protocols influences robustness of radiomic analyses. The aim of this study was to investigate the influence of different CT-scanners, slice thicknesses, exposures and gray-level discretization on radiomic feature values and their stability.Material and methods: A texture phantom with ten different inserts was scanned on nine different CT-scanners with varying tube currents. Scans were reconstructed with 1.5 mm or 3 mm slice thickness. Image pre-processing comprised gray-level discretization in ten different bin widths ranging from 5 to 50 HU and different resampling methods (i.e., linear, cubic and nearest neighbor interpolation to 1 × 1 × 3 mm3 voxels) were investigated. Subsequently, 114 textural radiomic features were extracted from a 2.1 cm3 sphere in the center of each insert. The influence of slice thickness, exposure and bin width on feature values was investigated. Feature stability was assessed by calculating the concordance correlation coefficient (CCC) in a test-retest setting and for different combinations of scanners, tube currents and slice thicknesses.Results: Bin width influenced feature values, but this only had a marginal effect on the total number of stable features (CCC > 0.85) when comparing different scanners, slice thicknesses or exposures. Most radiomic features were affected by slice thickness, but this effect could be reduced by resampling the CT-images before feature extraction. Statistics feature ‘energy’ was the most dependent on slice thickness. No clear correlation between feature values and exposures was observed.Conclusions: CT-scanner, slice thickness and bin width affected radiomic feature values, whereas no effect of exposure was observed. Optimization of gray-level discretization to potentially improve prognostic value can be performed without compromising feature stability. Resampling images prior to feature extraction decreases the variability of radiomic features.

Optimization of the SDS-PAGE gel slicing approach for identification of human liver microsomal proteins via MALDI-TOF mass spectrometry

Proteomics often exploits sequential cutting of the SDS-PAGE gel lane into slices with subsequent identification of proteins by peptide mass fingerprinting (PMF). In this paper, the influence of slice thickness on protein identification was investigated. Following the separation of the human liver microsomal fraction, the 37 to 75 kDa range of the gel lane was cut into 20 or 40 slices of 0.5 mm and 0.25 mm thickness, respectively. Identification of proteins after trypsinolysis was performed by MALDI-TOF mass spectrometry. A twofold reduction of slice thickness did not influence the number of peaks in PMF-spectra. It was established that at a tolerance of 0.15 Da the number of identified proteins in the 40 slices series exceeded by more than twofold the number of identifications in 20 slices series. It was shown that the decrease of slice thickness leads to a considerable enhancement of peptide peak’s intensity and, also, to the changes of PMF-spectra which resulted gaining additional peptides for enrichment of sequence coverage.

Influence of Slice Thickness on Diagnoses of Pulmonary Nodules Using Low-dose CT: Potential Dependence of Detection and Diagnostic Agreement on Features and Location of Nodule

The aims of this study were to assess the influence of slice thickness on the ability of radiologists to detect or not detect nodules and to agree or disagree on the diagnosis and also to investigate the potential dependence of these relations on the sizes, average computed tomographic (CT) values, and locations of the nodules.Six radiologists performed qualitative diagnostic readings of multislice CT images with a slice thickness of 2 or 10 mm obtained from 360 subjects. The nodules were diagnosed as nodules for further examination (NFEs), inactive nodules for no further examination (INNFEs), or no abnormality. The results of the diagnoses were cross-tabulated and quantitatively analyzed using the average CT values, sizes, and locations of the nodules with reference to the 2-mm slices. Multivariate logistic regression analyses were used to estimate the significant associations of these parameters with the ability of radiologists to detect or not detect nodules and to agree or disagree on the diagnosis.Totals of 130 NFEs and 403 INNFEs for 2-mm slice thickness and 142 NFEs and 338 INNFEs for 10-mm slice thickness were diagnosed. Nodule classifications were as follows: the same diagnosis on both slice thickness images (67.6%), different diagnoses on two slice thickness images (21%), missed on 10-mm slice thickness images (10.6%), and misinterpreted on 10-mm slice thickness images (0.7%). Regarding detection and nondetection, NFE diagnoses were influenced by size (odds ratio [OR], 132.50; 95% confidence interval [CI], 4.77-4711) and the average CT value (OR, 27.20; 95% CI, 3.21-645.3), and INNFE diagnoses were influenced by size (OR, 16.10; 95% CI, 6.18-55.19) and the average CT value (OR, 7.67; 95% CI, 2.19-30.91). Regarding diagnostic agreement and disagreement, the NFE diagnoses were influenced by size (OR, 3.60; 95% CI, 1.29-11.04), nodule distance from the lung border (OR, 2.85; 95% CI, 1.27-6.65), and nodule location in the right upper lobe (OR, 0.07; 95% CI, 0.003-0.477), while the INNFE diagnoses were influenced by the average CT value (OR, 11.84; 95% CI, 3.33-55.86), size (OR, 0.42; 95% CI, 0.25-0.70), and nodule distance from the lung border (OR, 0.41; 95% CI, 0.25-0.66).The influence of slice thickness on the ability of radiologists to detect or not detect nodules and to agree or disagree on the diagnosis was quantitatively evaluated. Detection and nondetection of NFEs and INNFEs are influenced by size and average CT value. Agreement and disagreement on NFE and INNFE diagnoses are influenced not only by size and average CT value but also, importantly, by the locations of nodules.

Influence of slice thickness on MR flow quantification in turbulent jets

Magnetic Resonance (MR) based flow quantification is of high interest in several cardiac diseases, e.g. valvular stenosis. However, accurate results remain challenging in several conditions. Recently, some contributors could be defined including echo time [1] (TE) and background phase errors [2]. We investigated the influence of slice thickness on flow quantification in turbulent flow.

Influence of slice thickness and reconstruction kernel on the computed tomographic attenuation of coronary atherosclerotic plaque

The computed tomographic (CT) attenuation of coronary atherosclerotic plaque has been proposed as a marker for tissue characterization and may thus potentially contribute to the assessment of plaque instability. We analyzed the influence of reconstruction parameters on CT attenuation measured within noncalcified coronary atherosclerotic lesions. Seventy-two patients were studied by contrast-enhanced dual-source CT coronary angiography (330 millisecond rotation time, 2 x 64 x 0.6 mm collimation, 120 kV, 400 mAs, 80 mL contrast agent intravenously at 6 mL/s), and a total of 100 distinct noncalcified coronary atherosclerotic plaques were identified. Image data sets were reconstructed with a soft (B20f), medium soft (B26f), and sharp (B46f) reconstruction kernel. With the medium soft kernel, image data sets were reconstructed with a slice thickness/increment of 0.6/0.3 mm, 0.75/0.4 mm, and 1.0/0.5mm. Within each plaque, CT attenuation was measured. Mean CT attenuation using the medium soft kernel was 109 +/- 58 HU (range, -16 to 168 HU). Using the soft kernel, mean density was 113 +/- 57 HU (range, -13 to 169 HU), and using a sharp kernel, mean density was 97 +/- 49 HU (range, -23 to 131 HU). Similarly, reconstructed slice thickness had a significant influence on the measured CT attenuation (mean values for medium soft kernel: 102 +/- 52 HU versus 109 +/- 58 HU versus 113 +/- 57 HU for 0.6-mm, 0.75-mm, and 1.0-mm slice thickness). The differences between 0.75-mm and 0.6-mm slice thickness (P = 0.05) and between medium sharp and sharp kernels (P = 0.02) were statistically significant. Image reconstruction significantly influences CT attenuation of noncalcified coronary atherosclerotic plaque. With decreasing spatial resolution (softer kernel or thicker slices), CT attenuation increases significantly. Using absolute CT attenuation values for plaque characterization may therefore be problematic.

Automated volumetry of pulmonary nodules on multidetector CT: influence of slice thickness, reconstruction algorithm and tube current. Preliminary results

To evaluate the influence of slice thickness, reconstruction algorithm and tube current (mA) on the performance of a software package in determining the volume of solid pulmonary nodules on multidetector-row computed tomography (MDCT). A chest phantom containing artificial solid nodules with known volume was imaged with two MDCT scans at 100 and 40 mAs (200 mA and 80 mA, 0.5-s rotation time), respectively. Data were reconstructed with slice thicknesses of 1.25 and 2.5 mm and five different algorithms. The volumes of three nodules (juxtavascular, intraparenchymal, juxtapleural) were calculated using three-dimensional (3D) volumetric software. Differences between estimated and real volume were reported for each nodule and reconstruction set. The software segmented all nodules on 1.25-mm-thick reconstructions, independently from the mAs. It did not segment the juxtapleural nodule on 2.5-mm-thick reconstructions at 40 mAs. Mean values of the differences, which better approximated the real volume of the nodules, were obtained with high-spatial-resolution algorithms on both 100 and 40 mAs images at 1.25-mm slice thickness. Slice thickness, reconstruction algorithm and tube current can affect the 3D volume measurement of solid nodules. The best performance of the software, on both 100 and 40 mAs images, was observed with a slice thickness of 1.25 mm and high-spatial-resolution algorithms.

Reproducibility of CT-based bone texture parameters of cancellous calf bone samples: Influence of slice thickness

Bone microarchitecture is an important determinant of the fracture risk, independently of bone mineral density. At present, bone biopsy is required for microarchitecture assessment, and accessible non-invasive techniques are needed. In this study, we tested the short-term reproducibility and parameter changes of a non-invasive method for microarchitecture assessment with a medical computed tomography. Texture parameters (run lengths and co-occurrence) were extracted from bone sample images. Reproducibility and the influence of slice thickness (1, 3, 5 and 8 mm) were also studied. After five repositionings, short-term reproducibility was found to be good. All run length parameters but one fell significantly with increasing slice thickness. Co-occurrence parameters showed different patterns of change. Short-term coefficients of variation of texture parameters used to assess bone microarchitecture were similar to those obtained elsewhere with other techniques. The results were influenced by slice thicknesses, emphasizing the importance of the conditions of acquisition.

Volumetrical Measurements in Vestibular Schwannoma, the Influence of Slice Thickness and Patient's Repositioning

Conservative treatment in vestibular schwannomas is mainly dependent on optimal tumor size determination. The first objective of this study was to establish interobserver and intraobserver variability and the accuracy and reproducibility of three different measurement methods: one bidimensional and two volumetrical. The second objective was to evaluate the influence of the use of different magnetic resonance imaging (MRI) slice thickness and the influence of patient's repositioning on the measurements' outcome. Two consecutive studies have been prospectively performed, both mainly concerning volumetrical measurements. Both studies were performed in a tertiary academic, multidisciplinary center. In the first study, 19 patients were included between March 1996 and May 2002, with a total of 52 scans. The second study comprised 14 patients. All patients in the first study had at least two MRI examinations performed according to a standard protocol (T1-weighted gadolinium-enhanced, slice thickness of 3 mm, and interslice gap of 0.3 mm). The population in the second study underwent a conservative wait and scan (W&S) treatment. Both studies are discussed separately. In the first study, all scans were measured by four investigators, two of whom performed the measurements twice using three different methods. The first method concerns a manually performed bidimensional surface measurement along the petrous pyramid. The second method concerns a semiautomatic volumetrical measurement on a computer, relying on contour detection, and the last method concerns a fully automatic volume reconstruction also performed on a computer using different gray shade scales. All 14 patients included in the second study underwent three magnetic examinations. Three different T1-weighted gadolinium-enhanced sequences were used: the first using a slice thickness of 1 mm, the second again with 1-mm slice thickness but after having repositioned the patient. In the third sequence, a slice thickness of 3 mm was used. All scans were measured by two investigators using the three different methods, as described previously. The manual surface method shows large intraobserver variability, and its reproducibility is significantly lower compared with volume measurements. Because of a relatively large systematic error in small tumors, sensitivity of growth detection is low. Both volumetrical methods are hardly interobserver- and intraobserver-dependent, and the gray shade method turned out to be the most accurate. Radiologic progression is only significant at a volume increase of at least 50%. The influence of patient repositioning is negligible, whereas the use of 1-mm slice thickness seems to be superior to a 3-mm slice thickness. The volumetrical gray shade method is the most accurate method to detect early tumor progression. As tumor increase of at least 50% is needed to be able to speak of statistically significant tumor growth, the absence of radiologic progression does not mean that there is no tumor growth. Repositioning of the patient has no influence on the measurements' outcome, whereas for optimal magnetic resonance imaging examinations, a 1-mm slice thickness protocol seems to be superior.

The influence of slice thickness on assessment of clavicle ossification in forensic age diagnostics

Computed tomography scans originally obtained to assess the ossification status of the medial clavicular epiphyses of 40 live subjects for forensic age estimation purposes were analysed. From the data acquired we reconstructed images with slice thicknesses of 1, 3, 5 and 7 mm, and based on the classification of stages by Schmeling et al. (Int J Legal Med 118:5-8, 2004), we determined the ossification stage for each reconstructed slice thickness, separately for both sides. Of the 80 clavicular epiphysial plates examined, seven displayed slice-thickness-dependent differences at certain ossification stages. In one case a slice thickness of 1 mm led to a different diagnosis of the ossification stage than a slice thickness of 3 mm, in three cases the diagnoses differed between the slice thicknesses of 3 and of 5 mm, and in another three cases, between 5 and 7 mm. We therefore conclude that for age estimation purposes, the slice thickness should be 1 mm to ensure maximum accuracy and diagnostic reliability.

The influence of slice thickness on the volume measurement accuracy of 3-D MR reconstructions of acrylic phantoms: a precursor to knee imaging

Purpose Publications regarding volume measurements derived from reconstructed three-dimensional (3-D) images have arisen from several research centres, yet only one example could be found of previous work specifically addressing the effect of acquisition slice thickness on the accuracy of such volume measurements in a musculoskeletal setting. Given the relative lack of previous work, as a precursor to clinical tissue trials, a phantom study was undertaken to examine the accuracy with which volume measurements could be made from 3-D reconstructed magnetic resonance (MR) images. We also wished to quantify the effect of acquisition slice thickness on resultant volume measurement accuracy. Methods A series of acrylic phantoms of varying known volumes (range: 990–21,450 mm 3) was scanned using T1-weighted MR images at slice thicknesses of 1.0, 2.0, 3.0, 4.0 and 5.0 mm. Four lesions (range: 61–212 mm 3) were milled into the surface of the largest phantom. Using a reconstructive software package, the scans obtained at each slice thickness were then used to create a 3-D computer model of the phantoms and lesions from which direct volume measurements were recorded. These measurements were then compared to the known volumes of the phantoms and a percentage measurement error (PME) was determined. Results The mean PME values recorded in the assessment of the phantoms decreased as acquisition slice thickness was reduced (10.84%, 8.27%, 4.86%, 2.80% and 0.59% for 5.0, 4.0, 3.0, 2.0 and 1.0 mm slices, respectively). An association between slice thickness and accuracy of volume measurement was shown (one-sample t-test: P<0.05). Discrete surface lesions were confidently recognised at all acquisition slice thickness although quantification at each level showed considerable variance. Conclusion The results of this study support the accepted inverse association between slice thickness and volume measurement accuracy. If a 5% level of PME is considered acceptable, the findings suggest that slice thicknesses of 3.0 mm or less be employed where analysis of lesions estimated to fall within a volume range of 1000–20,000 mm 3 is being considered.

Influence of Slice Thickness and Culture Conditions on the Metabolism of 7-Ethoxycoumarin in Precision-cut Rat Liver Slices

This study investigated the effects of some experimental variables on the rate of xenobiotic metabolism in precision-cut rat liver slices. Liver slices of 123 ± 8μm (mean ± SEM of six slices), 165 ± 3μm, 238 ± 6μm and 515 ± 14μm thickness were prepared from male Sprague-Dawley rats, and incubated in RPMI 1640 medium in an atmosphere of 95% O2/5% CO2by using a dynamic organ culture system. Liver slices of all thicknesses metabolised 10μM 7-ethoxycoumarin to total (free and conjugated) 7-hydroxycoumarin in a time-dependent manner. The rate of 7-ethoxycoumarin metabolism was greatest in 165μm thick slices and slowest in 515μm thick slices, being 2.74 ± 0.19pmol/minute/mg slice protein and 0.69 ± 0.07pmol/minute/mg slice protein, respectively. No marked effects on the rate of 7-ethoxycoumarin metabolism in liver slices were observed either by changing the medium to Earle's balanced salt solution (EBSS) or by changing the gas phase to 95% air/5% CO2. Moreover, the perfusion of rat livers with EBSS at 2–4°C, prior to preparation of tissue cores, did not enhance 7-ethoxycoumarin metabolism in rat liver slices. In this study, the optimal slice thickness was 175μm, with higher rates of 7-ethoxycoumarin metabolism being observed than with 250μm thick slices, which are often used for studies of xenobiotic metabolism. Variable results were obtained with slices of around 100–120μm thickness, which may be attributable to the ratio between intact hepatocytes and cells damaged by the slicing procedure in these very thin slices.