William H. Nailon

Peripheral Tissue Involvement in Sporadic, Iatrogenic, and Variant Creutzfeldt-Jakob Disease An Immunohistochemical, Quantitative, and Biochemical Study

Human prion diseases are rare fatal neurodegenerative conditions that occur as acquired, familial, or idiopathic disorders. A key event in their pathogenesis is the accumulation of an altered form of the prion protein, termed PrP(Sc), in the central nervous system. A novel acquired human prion disease, variant Creutzfeldt-Jakob disease, is thought to result from oral exposure to the bovine spongiform encephalopathy agent. This disease differs from other human prion diseases in its neurological, neuropathological, and biochemical phenotype. We have used immunohistochemistry and Western blot techniques to analyze the tissue distribution and biochemical properties of PrP(Sc) in peripheral tissues in a unique series of nine cases of variant Creutzfeldt-Jakob disease. We have compared this with the distribution and biochemical forms found in all of the major subtypes of sporadic Creutzfeldt-Jakob disease and in a case of iatrogenic Creutzfeldt-Jakob disease associated with growth hormone therapy. The results show that involvement of the lymphoreticular system is a defining feature of variant Creutzfeldt-Jakob disease, but that the biochemical isoform of PrP(Sc) found is influenced by the cell type in which it accumulates.

Variant Creutzfeldt-Jakob disease: Immunocytochemical studies and image analysis

Variant Creutzfeldt‐Jakob disease (vCJD) is a recently identified human prion disease that appears to arise from exposure to the bovine spongiform encephalopathy agent. The clinical features and neuropathology of vCJD are distinctive, particularly the patterns of PrPsc accumulation in the brain. PrP immunocytochemistry has also demonstrated the accumulation of PrPsc in tissues outside the central nervous system, including sensory ganglia and lymphoid tissues. These observations have allowed the use of tonsillar biopsy as an investigation to aid the diagnosis of vCJD, since accumulation of PrPsc in lymphoid tissues does not occur in other forms of human prion disease. The patterns of PrPsc accumulation in vCJD can be studied by image analysis techniques, using both quantitative and qualitative approaches. Preliminary results of textural analysis are presented, which indicate that this approach can be used to discriminate and study the unique features of PrPsc accumulation in the brain in vCJD. This technique has major potential as a research tool in human prion diseases, particularly for the characterisation of disease phenotype in large series of cases. Microsc. Res. Tech. 50:2–9, 2000.

Characterisation of radiotherapy planning volumes using textural analysis.

Computer-based artificial intelligence methods for classification and delineation of the gross tumour volume (GTV) on computerised tomography (CT) and magnetic resonance (MR) images do not, at present, provide the accuracy required for radiotherapy applications. This paper describes an image analysis method for classification of distinct regions within the GTV, and other clinically relevant regions, on CT images acquired on eight bladder cancer patients at the radiotherapy planning stage and thereafter at regular intervals during treatment. Statistical and fractal textural features (N=27) were calculated on the bladder, rectum and a control region identified on axial, coronal and sagittal CT images. Unsupervised classification results demonstrate that with a reduced feature set (N=3) the approach offers significant classification accuracy on axial, coronal and sagittal CT image planes and has the potential to be developed further for radiotherapy applications, particularly towards an automatic outlining approach.

Targeted SERS nanosensors measure physicochemical gradients and free energy changes in live 3D tumor spheroids

Use of multicellular tumor spheroids (MTS) to investigate therapies has gained impetus because they have potential to mimic factors including zonation, hypoxia and drug-resistance. However, analysis remains difficult and often destroys 3D integrity. Here we report an optical technique using targeted nanosensors that allows in situ 3D mapping of redox potential gradients whilst retaining MTS morphology and function. The magnitude of the redox potential gradient can be quantified as a free energy difference (ΔG) and used as a measurement of MTS viability. We found that by delivering different doses of radiotherapy to MTS we could correlate loss of ΔG with increasing therapeutic dose. In addition, we found that resistance to drug therapy was indicated by an increase in ΔG. This robust and reproducible technique allows interrogation of an in vitro tumor-models bioenergetic response to therapy, indicating its potential as a tool for therapy development.

Identifying the dominant prostate cancer focal lesion using image analysis and planning of a simultaneous integrated stereotactic boost

ABSTRACT Background. Prostate cancer is now the only solid organ cancer in which therapy is commonly applied to the whole gland. One of the main challenges in adopting focal boost or true focal therapy is in the accurate mapping of cancer foci defined on magnetic resonance (MR) images onto the computerised tomography (CT) images used for radiotherapy planning. Material and methods. Prostate cancer patients (n = 14) previously treated at the Edinburgh Cancer Centre (ECC) were selected for this study. All patients underwent MR scanning for the purpose of diagnosis and staging. Patients received three months of androgen deprivation hormone therapy followed by a radiotherapy planning CT scan. The dominant focal prostate lesions were identified on MR scans by a radiologist and a novel image analysis approach was used to map the location of the dominant focal lesion from MR to CT. An offline planning study was undertaken on suitable patients (n = 7) to investigate boosting of the radiation dose to the tumour using a stereotactic ablative body radiotherapy (SABR) technique. Results. The non-rigid registration algorithm showed clinically acceptable estimates of the location of the dominant focal disease on all CT image data of patients suitable for a boost treatment. Standard rigid registration was found to produce unacceptable estimates of the dominant focal lesion on CT. A SABR boost dose of 47.5 Gy was delivered to the dominant focal lesion of all patients whilst meeting all dose-volume histogram (DVH) constraints. Normal tissue complication probability (NTCP) for the rectum decreased from 1.28% to 0.73% with this method. Conclusions. These preliminary results demonstrate the potential of this image analysis method for reliably mapping dominant focal disease within the prostate from MR images onto planning CT images. Significant dose escalation using a simultaneous integrated SABR boost was achieved in all patients.

Intravascular ultrasound image interpretation

In this study, statistical and fractal texture analysis was used to assess the ability of 30 MHz intravascular ultrasound (IVUS) data, in raw and scan-converted form, to characterise atherosclerotic plaque. Data from 3 different plaque groups was assessed in the study: 1) loose fibrotic tissue; 2) dense fibrotic tissue; and 3) calcium. The composition of each group was verified from histo-pathological analysis, providing a Gold Standard from which results were verified. Scan-converted images were used to locate 33 regions of interest (ROI) within areas of known tissue composition. Fractal and statistical textural features were computed on ROI data in raw and scan-converted form. The results show the ability of the method to discriminate between groups, in particular they highlight the advantage of using the raw data over the scan-converted data to assess coronary artery disease.

Texture analysis of 3D bladder cancer CT images for improving radiotherapy planning

At present no single texture analysis approach can provide automatic classification to the accuracy required for radiotherapy applications. The method presented was developed to classify areas within the gross tumor volume (GTV), and other clinically relevant regions, on computerized tomography (CT) images. For eight bladder cancer patients, CT information was acquired at the radiotherapy planning stage and thereafter at regular intervals during treatment. Textural features (N=27) were calculated on regions extracted within the bladder, rectum and a region identified as clinically relevant. The sequential forward search (SFS) method was used to reduce the feature set (N=3). The results demonstrate the significant sensitivity of the reduced feature set for classification of any orthogonal CT image and the potential of the approach for radiotherapy applications.

Fractal texture analysis: an aid to tissue characterisation with intravascular ultrasound

Coronary artery disease is a condition responsible for many acute coronary syndromes. The ability to categorise diseased arterial tissue belonging to distinct pathological groups would contribute to the understanding of the pathophysiologic structure of individual lesions, as well as making a significant contribution to treatment choice. Here, the authors investigate the use of fractal texture analysis techniques to assess the ability of 30 MHz intravascular ultrasound (IVUS) data, in raw form, to characterise intracoronary disease from samples of: foam cells (FC); foam cells containing lipid (LIP FC) and loose fibrotic tissue (LFT). Histological analysis was used to form a gold standard from which the results were verified. The results show inadequate discrimination of the sub-groups studied but highlight the need for a less comprehensive list of disease categories for discrimination with IVUS, where, it would appear that the resolution limitations of the imaging system prevent the original sub-groups defined by histological examination from being observed.

Application of Texture Analysis to Study Small Vessel Disease and Blood–Brain Barrier Integrity

Objectives We evaluate the alternative use of texture analysis for evaluating the role of blood–brain barrier (BBB) in small vessel disease (SVD). Methods We used brain magnetic resonance imaging from 204 stroke patients, acquired before and 20 min after intravenous gadolinium administration. We segmented tissues, white matter hyperintensities (WMH) and applied validated visual scores. We measured textural features in all tissues pre- and post-contrast and used ANCOVA to evaluate the effect of SVD indicators on the pre-/post-contrast change, Kruskal–Wallis for significance between patient groups and linear mixed models for pre-/post-contrast variations in cerebrospinal fluid (CSF) with Fazekas scores. Results Textural “homogeneity” increase in normal tissues with higher presence of SVD indicators was consistently more overt than in abnormal tissues. Textural “homogeneity” increased with age, basal ganglia perivascular spaces scores (p < 0.01) and SVD scores (p < 0.05) and was significantly higher in hypertensive patients (p < 0.002) and lacunar stroke (p = 0.04). Hypertension (74% patients), WMH load (median = 1.5 ± 1.6% of intracranial volume), and age (mean = 65.6 years, SD = 11.3) predicted the pre/post-contrast change in normal white matter, WMH, and index stroke lesion. CSF signal increased with increasing SVD post-contrast. Conclusion A consistent general pattern of increasing textural “homogeneity” with increasing SVD and post-contrast change in CSF with increasing WMH suggest that texture analysis may be useful for the study of BBB integrity.

Comparative study of textural analysis techniques to characterise tissue from intravascular ultrasound

Thrombosis of coronary arteries is a condition responsible for many acute coronary syndromes. The ability to categorise thrombus belonging to distinct pathological groups, would contribute to the understanding of the pathophysiologic structure of individual lesions, as well as making a significant contribution to treatment choice. Here, the authors investigate the use of statistical texture analysis techniques to assess the ability of 30 MHz intravascular ultrasound (IVUS) data, in raw and scan-converted form, to characterise intracoronary thrombus. Three clot types were assessed in the study, these were, red (R), white (W) and plasma (P). Histopathological analysis, the de facto standard in identifying tissue composition, was used to form a Gold Standard based upon clot composition, from which the results were verified. The results show the ability of the texture analysis techniques used to discriminate clot lesions, and highlights the advantage of using the raw data over the scan-converted data in assessing thrombus composition in vitro.