Functional Diagnostic Techniques Research Articles

Methods and clinical significance of the condition of corneal nerve fibers

The review provides basic information about embryology, structural features, biochemical composition, functions and classification of corneal nerve fibers, and describes anatomical, histological and functional diagnostic techniques for corneal nerves. Each method for analyzing the structure of the nerve fiber, its advantages and disadvantages are described in detail, including the history of the development of confocal microscopy (laser and light) and esthesiometry (contact and non-contact). The article also presents the criteria according to which the structure of the nerve fiber is estimated using laser confocal microscopy, and the shortcomings of these criteria. Additionally, the article reports on the futility of the use of modern esthesiometry methods.

Target Adaptive Differential Iterative Reconstruction (TADI): A Robust Algorithm for Real-Time Electrical Impedance Tomography

Electrical impedance tomography (EIT) is a noninvasive functional diagnostic technique that has been successfully applied to human lung and brain. EIT reconstruction is an ill-conditioned problem: the regularization parameters establish a trade-off between acceptable data fitting and acceptable solution stability. This trade-off is necessary to select the optimal regularization parameters for each data frame to continuously obtain high-quality images in real-time monitoring. However, using the objective regularization parameter selection method before each image reconstruction may reduce the reconstruction efficiency, and using heuristic selection for all images may cause significant quality degradation, thereby creating challenges in long-term clinical EIT monitoring. This study explores a robust EIT target adaptive differential iterative reconstruction algorithm that does not require the advance selection of the optimal regularization parameter to facilitate the clinical application of EIT long-term bedside monitoring. Specifically, second-order Taylor approximation expansion and Euler–Lagrange theorem were used to derive the conductivity differential iteration relationship. Furthermore, the reconstruction quality and generalization ability of the proposed algorithm were validated based on comparisons with the L-curve and the generalized cross-validation parameter selection methods through simulations, phantom experiments, and human lung recruitment data. Compared with the L-curve and generalized cross-validation methods, the TADI algorithm reduces the position error by 33.07% and 47.17%, the ringing by 26.49% and 32.69%, and the shape deformation by 18.34% and 19.40% on average, respectively. The results revealed that the TADI algorithm could achieve a significant improvement over the existing state-of-the-art methods in terms of stability, consistency, and efficiency.

Functional diagnosis of placenta accreta by intravoxel incoherent motion model diffusion-weighted imaging.

To investigate the diagnostic value of intravoxel incoherent motion (IVIM) DWI for placenta accreta by comparing diffusion and perfusion characteristics of placentas with accreta lesions (APs) with those of normal placentas (NPs). Twenty-five pregnant women with AP and 24 with NP underwent 3-T magnetic resonance examinations with IVIM-DWI. The perfusion percentage (f), pseudo-diffusion coefficient (D*), and diffusion coefficient (D) values were calculated from different ROIs: the entire-plane of the AP (AP-ROI) and NP (NP-ROI) and the implanted (IR-ROI) and non-implanted region (NIR-ROI) of the AP. The AP-ROIs and NP-ROIs were compared using covariance analysis; the IR-ROIs and NIR-ROIs were compared using the Wilcoxon signed-rank test. ROC curves were produced to evaluate the parameters for predicting placenta accreta. The f and D* values for the AP-ROIs ([45.0 ± 7.63]%, [11.64 ± 2.15]mm2/s) were significantly higher than those for the NP-ROIs ([31.85 ± 5.96]%, [9.04 ± 3.13]mm2/s) (both p < 0.05); the IR-ROIs (54.8%, 14.03 mm2/s) were also significantly higher than the NIR-ROIs (37.4%, 11.4 mm2/s) (both p < 0.05). No significant differences were found between the D values of the AP-ROIs and NP-ROIs (p > 0.05) or of the IR-ROIs and NIR-ROIs (p > 0.05). The areas under the curve for f and D* of the ROC curves were 0.93 and 0.79, respectively. These results suggest that the IVIM parameters f and D* can be used to quantitatively evaluate the higher perfusion of AP when compared with NP. Furthermore, IVIM may be a useful functional diagnostic technique to predict placenta accreta. • Intravoxel incoherent motion (IVIM) may be a useful diagnostic technique to quantitatively estimate the perfusion of the placenta. • The perfusion percentage (f) and pseudo-diffusion coefficient (D*) values differed significantly between placentas with accreta lesions and normal placentas. • ROC curves showed that perfusion percentage (f) and pseudo-diffusion coefficient (D*) values could accurately predict placenta accreta.

Potential for Screening for Pancreatic Exocrine Insufficiency Using the Fecal Elastase-1 Test

The early diagnosis of pancreatic exocrine insufficiency (PEI) is hindered because many of the functional diagnostic techniques used are expensive and require specialized facilities, which prevent their widespread availability. We have reviewed current evidence in order to compare the utility of these functional diagnostic techniques with the fecal elastase-1 (FE-1) test in the following three scenarios: screening for PEI in patients presenting with symptoms suggestive of pancreatic disease, such as abdominal pain or diarrhea; determining the presence of PEI in patients with an established diagnosis of pancreatic disease, such as chronic pancreatitis or cystic fibrosis; determining exocrine status in disorders not commonly tested for PEI, but which have a known association with this disorder. Evidence suggests the FE-1 test is reliable for the evaluation of pancreatic function in many pancreatic and non-pancreatic disorders. It is non-invasive, is less time-consuming, and is unaffected by pancreatic enzyme replacement therapy. Although it cannot be considered the gold-standard method for the functional diagnosis of PEI, the advantages of the FE-1 test make it a very appropriate test for screening patients who may be at risk of this disorder.

A fully automatic, threshold-based segmentation method for the estimation of the Metabolic Tumor Volume from PET images: validation on 3D printed anthropomorphic oncological lesions

18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET) is a standard functional diagnostic technique to in vivo image cancer. Different quantitative paramters can be extracted from PET images and used as in vivo cancer biomarkers. Between PET biomarkers Metabolic Tumor Volume (MTV) has gained an important role in particular considering the development of patient-personalized radiotherapy treatment for non-homogeneous dose delivery. Different imaging processing methods have been developed to define MTV. The different proposed PET segmentation strategies were validated in ideal condition (e.g. in spherical objects with uniform radioactivity concentration), while the majority of cancer lesions doesn't fulfill these requirements. In this context, this work has a twofold objective: 1) to implement and optimize a fully automatic, threshold-based segmentation method for the estimation of MTV, feasible in clinical practice 2) to develop a strategy to obtain anthropomorphic phantoms, including non-spherical and non-uniform objects, miming realistic oncological patient conditions. The developed PET segmentation algorithm combines an automatic threshold-based algorithm for the definition of MTV and a k-means clustering algorithm for the estimation of the background. The method is based on parameters always available in clinical studies and was calibrated using NEMA IQ Phantom. Validation of the method was performed both in ideal (e.g. in spherical objects with uniform radioactivity concentration) and non-ideal (e.g. in non-spherical objects with a non-uniform radioactivity concentration) conditions. The strategy to obtain a phantom with synthetic realistic lesions (e.g. with irregular shape and a non-homogeneous uptake) consisted into the combined use of standard anthropomorphic phantoms commercially and irregular molds generated using 3D printer technology and filled with a radioactive chromatic alginate. The proposed segmentation algorithm was feasible in a clinical context and showed a good accuracy both in ideal and in realistic conditions.

Multifocal electroretinography: structural pattern analysis and early glaucoma detection

Glaucomatous optic neuropathy is probably one of the most prevalent chronic ophthalmologic diseases, affecting more than 5% of the population over 60 years of age. Early-stage glaucoma may be detected by studying local responses from many different areas of the retina, obtained by means of multifocal electroretinography (multifocal ERG), a new functional diagnostic technique. The described multifocal ERG waveform analysis, involved extracting waveform identity patterns and a neural network classifier, and allows detection of early glaucoma visual field defects.

Modeling of structure, quality, and function in the orthodontic patient.

The advantages of three-dimensional (3-D) imaging technology and solid modeling make it possible to visualize the morphological information. However, lacking in this 'digital patient' is the motion and mechanical properties observed in the living patient. Functional diagnostic techniques such as electromyography and motion analysis could complement the morphological characteristics to be applied in orthodontics. In this review, new computer-assisted analyzing methods are introduced which include visualization of: 1) the 3-D structure and bone density distribution; 2) masticatory-generated forces by using automated finite element modeling (FEM); and 3) the 3-D jaw movement and its motion analysis. In each study, the data from X-ray computed tomography scanning, electromyograms, biting pressure, and digital jaw movement analysis (six axes) are used for calculation. By using these applications, growing changes in bone mineral density distribution of the mandibular cortical bone have been clarified, automated finite element modeling has indicated stress distribution in the craniofacial skeleton, and patient-specific 3-D images of the mandible have been depicted as a motion picture. These studies were completed in 124 living subjects (75 females, 49 males) between 8 and 33 years of age. From these results, malfunctions during mastication were evaluated clearly with the individual patient craniofacial structures and its characteristics. These computer-based visualization techniques can be used to derive much clinically useful information, and to improve the combined evaluation of both static characteristics and dynamic function.

Long-term follow-up after in situ graft replacement in patients with aortofemoral graft infections

Aortic graft infection is among the most dreaded complications in vascular surgery. Regardless of management, it leads to high morbidity and mortality. Successful treatment traditionally involves removal of the infected prosthesis and revascularisation of the lower extremities by an extra-anatomic bypass. >3 Initial reviews of institutional series of patients with aortic graft infection emphasised the immediate postoperative mortality and morbidity. The long-term success of conventional treatment is measured in terms of patient survival, limb salvage and the abscence of complications related to graft excision, for example aortic stump blow-out. 4-1° As a treatment option for selected patients no clinical evidence of septicaemia or retroperitoneal purulent collections and no bacteriological evidence of pseudomonas infectionmany vascular surgeons now prefer in situ graft replacement of an infected aortic graft. ~>~9 Its long-term success should be measured in terms of persistent retroperitoneal infections that can develop even years after graft replacement. Late infectious complications most commonly arise in patients with primary graft infections caused by the less virulent micro-organism, for example coagulasenegative Staphylococcus epidermidis. 19 Hence the need for clinical and diagnostic imaging follow-up for reliable retroperitoneal surveillance. Newly introduced functional diagnostic techniques capable of detecting graft infections in their early stages, notably leukocytelabelled 99m HMPAO Technetium Scintigraphy (99mTc), seem to meet this requirement. 2°-22 We report a long-term follow-up (mean 37 months) of 18 patients, nine with an aortoenteric erosion (AEE)

Diagnosis of Diseases of the Chest (Third Edition, Vol 2)

This book integrates lung pathology and chest radiology and other diagnostic modalities. It also features over 50% new text and illustrations, including new techniques, comprehensive tables of differential diagnosis, investigative algorithms, and an updated, definitive pulmonary bibliography. It also covers the normal chest; methods of roentgenologic and pathologic investigation; clinical, laboratory, and functional diagnostic techniques; roentgenologic signs; and pulmonary abnormalities of development.

Current status of brain morphologic and related functional diagnosis in schizophrenic patients

Validity and interpretation of neuroradiological findings in schizophrenics are still discussed controversially. This applies also to some adjacent functional diagnostic techniques, which could possibly give support to neuroradiology, as post-mortem histopathological examination, electrophysiological recording, and positron-emission tomography. One of the causes for the inconclusive findings could be the patient- and control-group sampling, which is despite standardized diagnoses still heterogeneous in factors determining ventricular size. This heterogeneity applies also to the adjacent functional-diagnostic studies. A prevalence of enlarged ventricules of about 10% in schizophrenics is largely assumed, the measurements within the normal range tending to be somewhat higher than in the control-groups as well. Inconsistently a relation is reported between enlarged CSF-spaces on one side and unfavourable premorbid adjustment, chronic course of the illness, and predominance of negative symptoms on the other side. The CT findings in twin- and family studies stress also the etiological impact of brain morphology on schizophrenia. Size and width of ventricles in schizophrenics seem to be determined genetically as well as environmental. Most recently findings of unusual laterality or blurring of physiological lateral organization in the central nervous system gain growing interest. In this area brain-morphological findings are supported and supplemented by electrophysiological and PET-findings. For interpretation most authors at present refer to the hypothesis of 2 subgroups of schizophrenia, with and without dementing factors. The author suggests the view, that there is a common feature in all the heterogeneous and contradictory biological findings: They generally indicate a loss of cerebral organization.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked potentials and brain stem reflexes.

The recording of evoked potentials (EPs) has become one of the most useful functional diagnostic techniques in the neurosciences during recent years. In combination with the neurophysiological investigation of brain stem reflexes (BSRs) EPs provide good information concerning circumscribed and diffuse brain and brain stem lesions. In this article the role of EPs and BSRs will be pointed out with special regard to their use in neurosurgery concerning awake and comatose patients as well. Pathological findings caused by extracerebral factors or due to neurological (systemic) and otological diseases will be discussed from the aspect of differential diagnosis only. Evoked potentials described in this paper are short latency potentials which are related to more or less defined generators in the peripheral and central nervous system. EPs of long latency seem to play a role in cognitive, affective and integrative functions of the central nervous system and they will not be dealt with in this article. In recent years an increasing number of review articles and monographs dealing with several aspects of evoked potentials has appeared [16, 17, 18, 25, 69, 80, 84, 122, 123, 124, 127, 130].