The microcomputer and image analysis in diagnostic pathology

This paper presents a snapshot view of the influence and direction of microcomputer technology for image analysis techniques in diagnostic pathology. Microcomputers have had considerable impact in bringing image analysis to wider application. Semi-automated tracing techniques are a simple means of providing objective data and assist in a wide range of diagnostic problems. From the common theme of reducing subjectivity in diagnostic assessment, an extensive body of research has accrued. Some studies have addressed the need for quality control for reliable, routine application. Video digitizer cards bring digital image analysis within the reach of laboratory budgets, providing powerful tools for investigation of a wide range of cellular and tissue features. The use of staining procedures compatible with quantitative evaluation has become equally important. As well as assisting scene segmentation, cytochemical and immunochemical staining techniques relate the data to biological processes. With the present state of the art, practical use of microcomputer based image analysis is impaired by limitations of information extraction and specimen throughput. Recent advances in colour video imaging provide an extra dimension in the analysis of multi-spectral stains. Improvements will also be felt with predictable increase in speed of microprocessors, and with single chip devices which deliver video rate processing. If the full potential of this hardware is realized, high-speed, routine analysis becomes feasible. In addition, a microcomputer imaging system can play host to companion functions, such as image archiving and transmission. With this outlook, the use of microcomputers for image analysis in diagnostic pathology is certain to increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Video image analysis of AgNOR distribution in the normal and adenomatous colorectum

The nucleolar organizer regions (AgNORs) have been studied by video image analysis in the normal colorectum and in adenomas arising there. Total AgNOR area was measured in conjunction with the total area of nuclei and expressed as a ratio. AgNORs are found to predominate in the proliferative regions of the normal mucosal crypt, and the ratio of AgNOR to nuclear area proved significantly greater in the normal colon than in the rectum and far greater in colorectal adenomas. Further, there is a significant difference between the ratio in tubular as opposed to villous patterns of adenomatous growth in the colon but not in the rectum. When classified according to their degree of dysplasia, adenomas in the rectum exhibit a significantly higher ratio of AgNOR to nuclear area as the degree of dysplasia increases in severity. This correlation is not shown in the colon.

Two methods of assessment of methotrexate hepatotoxicity in patients with rheumatoid arthritis

Serial liver biopsy specimens from 18 patients with rheumatoid arthritis receiving a weekly dose of methotrexate 7.5-20 mg for a minimum of 12 months were assessed semiquantitatively and by a microcomputer image analysis system. The semiquantitative histological method showed a significant increase in pericellular collagen and in overall disease while morphometry showed a significant increase in pericellular, perivenular, and portal tract collagen. There was a significant correlation between the two methods, but morphometry had the advantage of objectivity and efficiency. There was no correlation between the increase in collagen and the accumulated dose of methotrexate, which suggests that other factors in addition to methotrexate may contribute to liver injury.

The use of computer-assisted video image analysis in the enumeration of immuno-stained cells in tissue sections

A novel method of computer-assisted video image analysis (VIA) was used to determine the number of immunostained cells in tissue sections. This method permitted an accurate and objective quantification of cells of a particular phenotype. This enumeration was achieved by measuring the area stained by a test monoclonal antibody (such as the T cell marker, CD3) and comparing it with the area stained by a leukocyte common (LCA) monoclonal antibody (CD45). The proportion of T cells within the total leukocyte population in a particular tissue was then calculated. The differentiation of positive (stained) and negative (unstained) cells was uniformly maintained by setting the computer to detect a threshold for staining intensity. This enabled consistency to be maintained within a tissue section as well as between sections stained with the same antibody. In the present study, we determined the phenotype of leukocytes in colonic carcinomas by VIA and compared this with results obtained by normal visual analysis. The VIA method showed distinct advantages over normal visual analysis especially in sections which contained moderate numbers of stained cells.

S100 protein, neurone specific enolase, and nuclear DNA content in Spitz naevus

The differentiation between Spitz naevus and melanoma is at times difficult. The present study was undertaken to define means to positively identify such melanocytic tumours of doubtful malignancy. Immunohistochemical staining intensity for S100 protein and neurone specific enolase (NSE) was measured in sections of 35 Spitz naevi using a microcomputer image analysis system. The data were compared with results previously obtained from 19 cases of malignant melanoma and 16 benign compound naevi. Disaggregated cells from paraffin-embedded material were stained by the Feulgen technique for DNA estimation. The nuclear DNA content distributions were measured using the same image analysis system. Compared with the malignant cases, the Spitz naevi showed significantly lower staining intensity for both S100 protein (P less than 0.0001) and NSE (P less than 0.0001). When compared with the benign compound naevi, the staining intensity was significantly lower for S100 protein (P = 0.003). The nuclear DNA distribution in Spitz naevi proved to be a normal diploid pattern in 31 cases. Four cases showed a small proportion of hyperdiploid nuclei. The results show that Spitz naevi can be significantly distinguished from malignant melanoma by staining intensity for S100 protein and NSE. A normal diploid DNA content distribution appears to be typical for Spitz naevi. Spitz and benign compound naevi show dissimilar expression of S100 protein which may indicate different patterns of differentiation in these two types of lesion. The image analysis equipment used in this study is accurate, simple to use, produces results rapidly, and is economic. Therefore, it is clinically practicable.

Density and phenotype of tumour-associated mononuclear cells in colonic carcinomas determined by computer-assisted video image analysis

The density and phenotypes of tumour-associated mononuclear cells (TAMC) in tissue sections of colonic carcinomas was determined by the technique of video image analysis (VIA). This technique allowed an accurate and objective enumeration of both total mononuclear cells (MC) in H&E stained sections and individual types of cells as revealed by immunoperoxidase staining with monoclonal antibodies in frozen sections. This enumeration allowed reliable statistical analysis of the differences between sample groups. Using this technique it was found that the density of MC in histiologically normal tissue was significantly higher than in tumour tissue. Tumours from patients with the best prognosis (stage A) had significantly higher numbers of TAMC than stage B (P less than 0.02), C (P less than 0.002) and D (P less than 0.002) tumours. The differences in the density of TAMC between tumours obtained from stage B and C and that between C and D were not significant, whereas stage B had a significantly higher TAMC density than stage D tumours (P less than 0.05). Comparing tumour differentiation, well differentiated adenocarcinomas had a significantly higher (P less than 0.05) TAMC density than poorly differentiated tumours but not moderately differentiated tumours. Moderately and poorly differentiated adenocarcinomas did not differ significantly in the density of TAMC. In examining the phenotype of these cells, it was found that T lymphocytes formed the majority of the TAMC with the CD4+ subset predominating in 28 of 29 cases. Similarly, all sections of normal colon (taken at least 4 cm away from the tumour) had more CD4+ than CD8+ cells. The proportion of the total leucocyte population that was CD3+ was comparable in normal and tumour tissue. Generally, few macrophages were present in either tumour or normal tissues. B cells (CD21%) and subset of NK cells (CD57+) were not detected in the tumours. There were no significant differences in the proportion of leucocytes which were CD4+, CD8+ and CD14+ (macrophages) between the normal colon and the tumour tissues. The types of cells in the TAMC population did not differ with tumour stage or differentiation or with the density of the TAMC itself.

Morphometric analysis of nuclear features, ploidy status, and staging in rectal carcinoma

Recently, several flow cytometric studies have shown that the nuclear DNA content in colorectal carcinoma gives prognostic information which is independent of that provided by the histological characteristics of the tumour. In this study the nuclear DNA content and nuclear morphology of 39 cases of surgically resected rectal adenocarcinoma were measured in Feulgen-stained histological sections by video image analysis and 97 per cent were aneuploid. Dukes' stage correlated better with the morphometric data than did other classification systems. The extent of local spread and the growth pattern at the invasive margin of the tumour, which are of known prognostic importance, were significantly related to some nuclear features. Discriminant analysis of the nuclear morphometric data alone was highly successful in predicting these tumour characteristics. The results suggest that routine application of this technique to tumour biopsies may be of value in patient management since it provides stage-related information which cannot be obtained by conventional histopathological assessment.

Nuclear indices and survival in cutaneous melanoma

Computerized video image analysis of Feulgen-stained paraffin sections was used to assess the relationships of nuclear DNA content and other nuclear morphological characteristics with survival from cutaneous melanoma. The results indicate that nuclear area and deviation from diploidy have effects on survival independent of tumor thickness and the age of the patient. Tumor thickness, however, remained the most important predictor of survival. Video image analysis of tissue sections, by virtue of its speed, simplicity, and accuracy, appears to be a potentially valuable prognostic method.

Immunocytochemical assay for oestrogen receptor in fine needle aspirates of breast cancer by video image analysis

Assessment of heterogeneity in oestrogen receptor (ER) expression aims to improve prediction of prognosis and treatment assignment in breast cancer. Current assessments are performed manually and are subjective. Automated image analysis as described here objectively quantitates ER in breast cancer nuclei obtained by needle aspiration. ER was visualised by ERICA with diaminobenzidine (DAB) substrate. Various indices of ER positivity were derived from the integrated density and average density measurements of nuclear DAB. Each index was compensated for background staining by non-specific antibody binding and endogenous peroxidase activity. Total nuclear ER content (integrated optical density of stain) was strongly associated with the biopsy ER concentration determined by saturation analysis of radioligand binding (DCC), P less than 0.005. Nuclear ER concentration by image analysis (mean optical density of stain) was not associated with the DCC measurement of ER concentration, P greater than 0.05. This was attributed to technical artefacts of cytocentrifugation. Using threshold values of 5% positive cells and 10 fmol mg-1 concordance of assignment of ER status by image analysis with the DCC assay was 91%, sensitivity was 89% and specificity 100%. It was concluded that image analysis is an appropriate, easy and economic method for determining the nuclear ER status of aspirated cancer cells. Image analysis has the potential to become a powerful diagnostic tool in the assessment of hormone receptor status of breast cancer patients.

Preliminary studies on scoring micronuclei by computerised image analysis

Initial studies of the use of computerised image analysis to determine micronucleus frequencies in human lymphocytes that have completed one nuclear division are described. Two methods, based on (a) bromodeoxyuridine incorporation and (b) cytokinesis blocking with cytochalasin-B, were studied. The former method is directly amenable to automation. Cytokinesis-blocked cells could not be automatically recognised by image analysis but it was possible to obtain the correct micronucleus frequency from the integrated optical density histograms by using the mononucleate/binucleate cell ratio obtained by visual analysis. The mean (+/- 1 S.E.) integrated optical density of X-ray-induced micronuclei was 11.2% (+/- 1.1) of that measured for nuclei of G1 cells.

Correlation of nuclear ploidy with histology in adenomatous polyps of colon

Histological sections of adenomatous polyps of the colon showing carcinoma were studied by video image analysis. Nuclear DNA content and morphology were measured in regions identified as either dysplasia, carcinoma confined to the mucosa, or carcinoma invading the muscularis mucosa. Where carcinoma was present, areas of dysplasia in the same polyp were found to have similar distributions of nuclear DNA content and size, supporting the notion that adenomatous polyps becomes cancer. The method can be used to detect those regions in sections of adenomatous polyps with the most severe nuclear abnormality.

Measuring S100 protein and neurone specific enolase in melanocytic tumours using video image analysis

Using a computed video image analysis system, the staining intensity for both neurone specific enolase (NSE) and S100 protein was measured in sections from 19 malignant melanomas and 16 benign melanocytic lesions. The results of this study confirm previous reports that NSE and S100 protein are useful markers for malignant melanoma. NSE staining intensity in the cases of malignant melanoma was significantly higher than that in benign naevi (p = 0.011). Intensity of staining for S100 protein was not significantly higher in the malignant melanomas. There was, however, a significant S100 gradient when comparing superficial and deep intradermal portions of these tumours (p = 0.003). This feature was not seen in benign naevi. The greatest intensity of S100 protein staining was found in the deeper portions of the malignant melanomas. This gradient difference was not seen with staining for NSE. Although it seems that the overall intensity of staining for NSE is more effective in differentiating between benign and malignant lesions, the difference in staining intensity between the superficial and deep portions of the tumour may be the better indicator of adverse behaviour in lesions in which the diagnosis of malignancy is uncertain.

Glomerular basement membrane abnormalities associated with apparently idiopathic hematuria: ultrastructural morphometric analysis

In a recent review of 480 renal biopsies, 41 cases were identified in which glomerular basement membrane (GBM) ultrastructural abnormalities were the major lesion. All of the patients had hematuria. None had evidence of immune-mediated glomerulonephritis. Positive family histories of renal disease were present in the majority of cases, and one case of Alport's syndrome was included. Subjectively, the GBM changes were variable but nearly always included membrane thinning. For objective characterization of this glomerular abnormality, a detailed morphometric study of GBM thickness was undertaken: 12 of these patients (study group) were compared with seven patients (control subjects) with subjectively normal glomeruli who underwent biopsy for reasons other than nonsurgical hematuria but who were also thought to have normal glomerular ultrastructure. The seven control subjects had a mean GBM thickness of 394 nm (SD, 19; range, 356 to 432 nm). Of the 12 study group patients, 11 had mean GBM thicknesses significantly different from control values (nine had mean GBM thinning: range, 235 to 327 nm; two had thickening: means, 440 and 469 nm). In the remaining case (Alport's syndrome) the overall mean was normal, but an abnormal distribution of very thin and very thick GBM regions was seen. Of the four apparently normal hematuric patients, significant mean GBM thinning (326 to 347 nm) was demonstrated in three, with an excess of thin GBM in the fourth case, although the mean thickness was normal. Thus, measurable abnormalities were defined in all of the cases of hematuria examined. The GBM measurements confirmed the subjective impression of membrane abnormality, usually attenuation, as the principal finding in this group of hematuric patients. Furthermore, morphometric analysis may reveal subtle changes of GBM thickness missed by subjective assessment.

A microcomputer system for video image analysis and diagnostic microdensitometry

A system for microdensitometry based on a microcomputer, video digitizer and solid-state camera has been developed. Image analysis and densitometry are achieved with convenient control over image editing and calibration. The linear photometric properties of the imaging device enable measurements of high accuracy. The system has proven to give rapid and repeatable performance for determining DNA content distribution from measurements of Feulgen-stained cell nuclei. The results show that a practical image analysis microdensitometer can be designed using a readily available microcomputer. The low cost and simple operation are of benefit for diagnostic applications in which flow cytometry is not possible, the time required for microscope photometry is too great or an automated image analyzer and support staff are not available.

Ploidy studies in adenomatous polyps of the colon

The nuclei of colonic adenomatous polyps and some colonic carcinomas have a normal diploid profile. The remaining carcinomas are aneuploid, and this change most probably occurs after the dysplasia that determines invasiveness, because even adenomatous polyps with carcinoma in situ are diploid.

Morphometric analysis of gastric dysplasia

The grading of gastric epithelial dysplasia has been studied by means of computer aided morphometry. Measurements of histological features were made on segments of epithelium from 38 selected cases of dysplasia graded by subjective assessment. The measurements were statistically compared with the subjective scores using discriminant analysis. The measurements were found to provide significant discrimination between all groups. Nuclear size proved to be the main discriminating variable. Prediction of the likely group membership of individual cases was possible using classification equations derived from the discriminant analysis. Classification of the original data set revealed prediction errors which suggested a bias against diagnosis of dysplasia. As a result of this study reliable, repeatable and objective gradings of gastric epithelial dysplasia can be obtained by inexperienced persons with an accuracy approaching that of a skilled pathologist.

A morphometric classification of acute lymphoblastic leukemia in children

In order to reduce the subjective errors in subtyping leukemic lymphoblasts using the French-American-British (FAB) classification, computer-assisted morphometry was used. Bone marrow smears obtained at diagnosis from 99 children with acute lymphoblastic leukemia (ALL) were analysed by this method and compared with the subjective FAB classification. The results confirm that lymphoblast morphology, as a single variable, is a very significant predictor of survival in ALL. This computer-assisted morphometric analysis would be of great value in large-scale clinical trials in ALL.

Morphometric assessment of reflux oesophagitis in fibreoptic biopsy specimens

The oesophageal epithelium of patients with reflux oesophagitis has been studied by means of computer aided morphometry. Measurements of histological features were made on biopsies from six cases before and after treatment. The size and elongation of the nuclei and their variation, the number of nuclei per unit length or per unit sectioned area, and the size and number of nucleoli per nucleus were measured for two zones of the epithelium, the base layer and the intermediate layer, which were independent of section orientation. The measurements were analysed using discriminant analysis. Significant discrimination was found between the two groups. The most important parameters were the number of intermediate layer nuclei per sectioned square millimetre, the mean intermediate layer nuclear area, and the number of nuclei per millimetre of base epithelium. These parameters are consistent with increased cell turnover of the non-ulcerated epithelium before treatment.

The cellular response to human colonic neoplasms: macrophage numbers

Tumour cells and macrophages are thought to interact and the behaviour of tumours may be modified by macrophage activity. Using an immuno-histochemical method for the demonstration of lysozyme and a computerised image analysis system, the number of macrophages was assessed in and around tubulovillous adenomas and the different Dukes grades of adenocarcinomas of the colon. No significant differences were demonstrated and it is concluded that the behaviour of these neoplasms is not related to the number of associated macrophages.

Microdensitometry with image analyser video scanners

A numerical method for calibration of the Quantimet 720 1D Auto detector as a densitometer in absolute density units has been developed and applied to integrated microdensitometric measurement. A procedure for the estimation and correction of microscope glare error has also been derived. The error after glare correction was found to be comparable with threshold setting variation encountered in routine use of the Quantimet. The method should prove valuable in densitometric applications not only for Quantimet image analysers but also for any instrument employing a video imaging system because the underlying principles are the same.

A staining method for the detection and measurement of fat droplets in hepatic tissue

The osmium tetroxide method for demonstrating lipid in human or animal tissue (Manual of Histological Staining Methods, 1968) has been modified to virtually eliminate background staining. Sections prepared by this method are suitable for either manual or automated analysis of the amount of fat tissue.

Effect of nicotine on the morphology of the rat gastric mucosa

The effect of oral nicotine dosage on the morphology of the rat gastric mucosa was studied. Cell populations, neck cell mucus volume fraction, and mucosal area and depth were measured, and differences in mean values for each group were tested for statistical significance. It was found that the equivalent of approximately 10 times the normal daily intake of nicotine achieved by human smoking is related to a significant decrease in total mucus neck cell population, neck cell mucus volume fraction and mucosal depth and to an increase in mucosal surface area. The nicotine doses caused no significant changes in the parietal or chief cell populations, body weight, or water consumption.

The development of the cuticle in Phormium tenax

As seen in the scanning electron microscope the surface wax of leaves of Phormium tenax L. consists of vertical, plate-like crystals. These increase in size and number and undergo a change in form during development. The abaxial surface has a dense covering of wax crystals, but none are present on the ridges over vascular tissues. Numerous papillae are found between these ridges in later stages of development. On the adaxial surface both wax crystals and papillae are present only around infrequent stomata.When viewed in section normal to the leaf surface the cuticle is first apparent as a thin, lamellate layer. Another layer containing a reticulum of electrondense material increases in thickness beneath the lamellae during development. This layer eventually becomes the most extensive component of the cuticle. Both the adaxial and abaxial cuticles show a similar pattern of development.