Kidney Tomosynthesis Image Reconstruction Algorithms and Image Quality Evaluation

Kidney stone disease is one of the most common diseases that faces the American population. For proper diagnosis of kidney stones medical imaging must be performed. The current gold standard for kidney stone detection is computed tomography (CT) imaging. However, CT imaging exposes the patient to large amounts of x-ray radiation. Digital tomosynthesis is a novel technique in medical diagnosis due to its ability to generate high-resolution images while limiting the radiation dosage to patients. Tomosynthesis is a three-dimensional imaging technique that allows the reconstruction of an arbitrary set of planes from limited-angle series of projection images. Tomosynthesis has well-published success in the field of breast and chest imaging but has had limited studies performed in field of kidney imaging. In this study, C-arm geometry tomosynthesis was compared to traditional tomosynthesis using the shift and add reconstruction algorithm to evaluate the effectiveness of C-arm tomosynthesis for the application of kidney imaging. A simulation was created to generate projection images of each geometry and implement the shift and add algorithm. The results showed that when the images were reconstructed there was more blurring using C-arm tomosynthesis as compared to traditional tomosynthesis. This indicates that C-arm tomosynthesis geometry has the potential to be developed with other reconstruction algorithms to make it better suited for implementation in kidney imaging. Furthermore, the simulations developed in this study lay the groundwork for future development of C-arm tomosynthesis by providing a platform to test new reconstruction algorithms and optimize system parameters for clinical applications

Magnetic Induction Tomography (MIT) simulation study for renal screening using different system frequencies and sizes of calcium oxalate

Nephrolithiasis is the process of forming stone in the kidney by crystallization. Due to the increasing prevalence of nephrolithiasis from time to time, medical institutions look for more advanced technology of medical imaging which can tackle the disadvantages of current medical imaging devices for renal, which are non-invasive, free radiation and rapid use. The research encompassed the design simulation study of Magnetic Induction Tomography (MIT) system for renal screening by using COMSOL multiphysics. MIT is a soft field tomography and a non-contact imaging modality used to image the passive electromagnetic properties (conductivity, permittivity and permeability) by applying principle of electromagnetic induction. In this research, 8 copper trans-receiver coils were employed in the MIT system and fixed by the insulation belt. Meanwhile, geometric set-up of renal organ imitates the transverse section at renal level of human body. Sensor performance analysis of MIT system was done based on various frequency and radius of calcium oxalate inside kidneys. In conclusion, frequency and radius of calcium oxalate affect the sensitivity performance of MIT system and has inverse relationship with sensitivity performance

Molecular Studies on Calcium Oxalate Kidney Stones: A Window into the Pathogenesis of Nephrolithiasis

Indiana University-Purdue University Indianapolis (IUPUI)Nephrolithiasis will affect one-in-eleven people, and more than half of those individuals will have stone recurrence within a decade of their first episode. Despite decades of biomedical research on nephrolithiasis and extraordinary advances in molecular and cell biology, the precise mechanisms of kidney stone formation are not fully understood. Currently, there are limited treatments or preventative measures for nephrolithiasis. Therefore, it is crucial to scrutinize kidney stones from a molecular and cell biology perspective to better understand its pathogenesis and pathophysiology; and to, hereafter, contribute to effective therapeutic targets and preventative strategies. Kidney stones are composed of an admixture of crystal aggregated material and an organic matrix. 80% of all kidney stones are composed of calcium oxalate (CaOx) and half of all CaOx patients grow their stones on to Randall’s plaques (RP). RP are interstitial calcium phosphate mineral deposits in the renal papilla. Thus, we developed and optimized methodologies to directly interrogate CaOx stones. CaOx stones were demineralized, sectioned, and imaged by microscopy, utilizing micro CT for precise orientation. Laser microdissection (LMD) of specific regions of stone matrix analyzed by proteomics revealed various proteins involved in inflammation and the immune response. Analyses on jackstone calculi, having arm protrusions that extend out from the body of the stone, revealed that they are a rare subtype of CaOx stone formation. Micro CT analyses on 98 jackstones showed a radiolucent, organic-rich core in the arm protrusions. Fluorescence imaging on RP stones showed consistent differences in autofluorescence patterns between RP and CaOx overgrowth regions. Moreover, cell nuclei were discovered with preserved morphology in RP regions, along with variable expressions of vimentin and CD45. In comparing spatial transcriptomic expression of reference and CaOx kidney papillae, CaOx patients differentially expressed genes associated with pathways of immune cell activation, reactive oxygen damage and injury, extracellular remodeling, and ossification. Our findings provide novel methodologies to better understand the role of molecules and cells in CaOx stone matrix. Several of the proteins and cells identified in these studies may serve as potential biomarkers, and future therapeutic targets in preventing kidney stone disease

Pseudo-monoenergetic x-ray diffraction measurements using balanced filters for coherent-scatter computed tomography

In the treatment of kidney stones, knowing stone composition has been established as an important aid to the understanding of stone formation and in preventing recurrences, particularly the composition of the initial “core” of the stone. Traditionally, stone composition has come from laboratory techniques such as infrared spectroscopy and x-ray diffraction. These methods require taking multiple samples of excised stone fragments and powdering them - losing structural information in the process, and therefore the specific core composition. Coherent-scatter computed tomography (CSCT) is a method of non-destructive “composition” imaging based on measurements of diffraction patterns from tissues. Use of an x-ray tube degrades scatter-pattern angular resolution due to the x-ray spectral width, making it difficult to uniquely identify some materials. The use of two transmission filters with similar atomic numbers (balanced “Ross filters”) to generate pseudo-monoenergetic scatter patterns of common kidney stone components is described as it applies to CSCT. We show that an analysis of angular-blur mechanisms reveals that focal spot size and beam width are the most important factors determining Bragg-peak width when erbium and thulium balanced filters are used. A Bragg-peak RMS angular width of approximately 0.14° (relative width of 3% at 5° scatter angle) can be achieved, reducing peak-overlap in the scatter functions of common kidney stone constituents. CSCT is capable of producing 3-D material-distribution maps. In previous studies, such maps were of relative material density. We describe a theoretical method to generate absolute (g/cm3) mass-density distributions. Balanced-filter CSCT improves scatter-function angular resolution and allows for the measurement of common kidney-stone constituents with non-overlapping peaks

A Study of Percutaneous Nephrolithotomy (PCNL) and grading of complexity of PCNL procedures using Guy's Stone Score.

INTRODUCTION : During the last two decades , the management of kidney stones has vastly changed. Prior to these modifications all the kidney stones were managed by open pyelolithotomy or nephrolithotomy which caused a significant morbidity for the majority of patient. Percutaneous Nephrolithotomy (PCNL) has now largely replaced open surgery as a safe and effective treatment for renal stones. It is now well recognized among surgeons that PCNL procedures have different degrees of complexity which affects stone clearance. The “Guy’s Stone Score” proposed by Thomas K and Smith et al, is a valuable tool to stratify the complexity of PCNL procedures into four groups based on the stone burden and the anatomy of both patient and renal tract. Grade I : Solitary stone in mid / lower pole or solitary stone in pelvis with simple anatomy. Grade II : Solitary stone in upper pole or multiple stones in patient with simple anatomy or solitary stone in patient with abnormal anatomy. Grade III : Multiple stones in a patient with abnormal anatomy or stones in a caliceal diverticulum or partial Staghorn calculus. Grade IV : Staghorn calculus or any stone in a patient with spina bifida/spinal injury. AIMS AND OBJECTIVES : To evaluate patients with renal stones at our institution. To study the indications for PCNL and to assess the outcome of procedure in patients with renal stones. To study the grading and complexity of PCNL procedures using “Guy’s Stone Score”. MATERIAL AND METHODS : 50 patients with symptomatic renal stones presenting to Urology OPD are evaluated and included in the study after informed consent. The indications for surgery are studied and patient is taken up for the same after anaesthetic fitness. PCNL is done using standard techniques. The complexity of procedure is graded using radiological studies and the outcome assessed based on “Guy’s Stone Score” and modified Clavien system. Inclusion Criteria: Patients with renal stone undergoing surgery-Percutaneous Nephrolithotomy. Exclusion Criteria: Patients not fit for surgery – bleeding diathesis, high cardiac risk, infection/ sepsis. CONCLUSION : In this study involving a relatively lesser number of cases from a tertiary care and resident training institute, the complication rates after PCNL was around 50 % mainly because of the learning curve in doing a new procedure. Most of the complications were minor which were treated conservatively. The Guy’s stones score predicted the stone free rates correctly with higher Guy’s stones score needing ancillary procedures mainly in the form of extracorporeal shock wave lithotripsy for stone clearance. Guy’s stones score correlated well with the modified clavien system of grading for perioperative complications. The Guy’s stone score is easy to use and reproducible. It can be used as an objective and reliable method for describing the complexity of PCNL predicting the stone free rate, and stratifying cases between surgeons of different experience and reporting results

Research Status and Prospect for CT Imaging

Computed tomography (CT) is a very valuable imaging method and plays an important role in clinical diagnosis. As people pay more and more attention to radiation doses these years, decreasing CT radiation dose without affecting image quality is a hot direction for research of medical imaging in recent years. This chapter introduces the research status of low-dose technology from following aspects: low-dose scan implementation, reconstruction methods and image processing methods. Furthermore, other technologies related to the development tendency of CT, such as automatic tube current modulation technology, rapid peak kilovoltage (kVp) switching technology, dual-source CT technology and Nano-CT, are also summarized. Finally, the future research prospect are discussed and analyzed

Basic Principles and Practice in Surgery

This publication aims to support young doctors and surgery residents during their training period. A surgical residency is a crucial period for a young doctor. A great volume of theoretical information along with difficult and demanding practical skills need to be acquired in a relatively short period of time. This book is a tool for rapid, correct acquisition of elementary surgical notions and techniques, which are the basis for the training of today's surgery resident

Assoziierte Begleiterkrankungen beim abdominalen Aortenaneurysma

Einleitung: Das abdominale Aortenaneurysma (AAA) ist eine Erkrankung des älteren Menschen. In Zeiten des demografischen Wandels gewinnt diese Erkrankung zunehmend an Bedeutung. Mit AAA werden bereits einige Erkrankungen in Verbindung gesetzt, u. a. Cholecystolithiasis (CCL), Nierenzysten, chronisch obstruktive Lungenerkrankung (COPD) und Hernien. Das Ziel dieser Arbeit ist es, neben bereits bekannten, auch neue mögliche assoziierte Begleiterkrankungen zum Krankheitsbild des AAA zu erfassen. Methoden: Die vorhandenen klinischen Daten von 100 AAA-Patienten wurden mit 100 Kontrollpatienten (gematcht nach Geschlecht und Alter) verglichen. Computertomographische Aufnahmen wurden von zwei unabhängigen Untersuchern auf das Vorhandensein von Nierenzysten, Leberzysten, Hernien, Divertikulose, CCL, A. lusoria und anderen Erkrankungen, wie z. B. Milzzysten, Pankreaszysten, Hiatushernie und Nephrolithiasis untersucht. Die Krankenakten wurden zur Ergänzung des Nebenerkrankungsprofils analysiert. Die statistische Auswertung erfolgte mittels univariater Analyse (Kreuztabellierung und Chi-Quadrat-Test) und multipler logistischer Regression. Ergebnisse: Die AAA-Patienten litten signifikant häufiger an Nierenzysten (p = 0,008) und Divertikulose (p = 0,008) und hatten häufiger eine Hernie in der Vorgeschichte (p = 0,005). Es wurde kein signifikanter Unterschied im Auftreten der Leberzysten (p = 0,609) und CCL (p = 1,000) festgestellt. Die AAA-Patienten litten ebenfalls häufiger an koronarer Herzkrankheit (KHK; p < 0,001), peripherer arterieller Verschlusskrankheit (pAVK; p = 0,037), Herzinsuffizienz (p < 0,001), chronischer Niereninsuffizienz (p < 0,001) und COPD (p < 0,001). Bei den AAA-Patienten wurde häufiger ein koronarer Bypass implantiert (p = 0,011), sie waren mit höherer Wahrscheinlichkeit ehemalige (p = 0,034) oder aktuelle (p = 0,006) Raucher und hatten eine signifikant höhere Zahl an pack years (p < 0,001). Diabetes mellitus trat in fortgeschrittenen Stadien häufiger in der Kontrollgruppe auf (p < 0,001). AAA-Patienten hatten eine signifikant niedrigere forcierte Einsekundenkapazität (p = 0,003), niedrigere Thrombozytenzahl (p = 0,030) und höhere Kreatininwerte (p = 0,032). In der multivariaten Analyse wurde eine direkte Assoziation von AAA mit folgenden Faktoren nachgewiesen: COPD (OR = 12,242; p = 0,002), chronischer Niereninsuffizienz (OR = 5,655; p = 0,003), aktuellem Nikotinabusus (OR = 4,141; p = 0,002), KHK (OR = 2,603; p = 0,020), Divertikulose (OR = 1,844; p = 0,075) und Thrombozyten (OR = 0,994; p = 0,023). Schlussfolgerung: Das Krankheitsbild des AAA ist bis zum heutigen Zeitpunkt leider immer noch nicht ausreichend genug untersucht worden. Umfassende Kenntnisse über das Krankheitsbild bilden die Basis für die zukünftige Entwicklung einer kurativen pharmakologischen Therapie. Durch eine weitere Erkennung neuer Risikofaktoren könnte das AAA in der Zukunft besser und früher erkannt werden. Eine Einführung eines gesetzlichen Screeningprogramms sollte in Erwägung gezogen werden.Background: Abdominal aortic aneurysm (AAA) is a disease of elderly people. In times of demographic change, this disease becomes increasingly important. There are some diseases that seem to be associated with AAA, e.g. cholelithiasis, renal cysts, chronic obstructive pulmonary disease (COPD), and hernia. The goal of the study is to assess diseases associated with AAA. Methods: Clinical data of 100 AAA-patients were compared with 100 controls (matched to sex and age). Computer tomographic scans were analysed by two independent examiners for the presence of simple renal cysts, liver cysts, hernia, diverticulosis, cholelithiasis, A. lusoria, and other diseases, e.g. spleen cysts, pancreas cysts, hiatus hernia, and nephrolithiasis. In addition, the patient data were analysed to complete the comorbidity profile. The statistical analysis included a univariate analysis (cross tabulation and Chi-Square-Test) and multiple logistic regression. Results: AAA-patients had higher prevalence of renal cysts (p = 0.008), diverticulosis (p = 0.008), and hernia (p = 0.005). There were no significant differences in prevalence of liver cysts (p = 0.609) and cholelithiasis (p = 1.000). AAA-patients had higher prevalence of coronary artery disease (CAD; p < 0.001), peripheral artery disease (p = 0.037), heart failure (p < 0.001), chronic kidney disease (CKD, p < 0.001), COPD (p < 0.001), and had a higher presence of coronary bypass (p = 0.011). AAA-patients were more frequent ex- (p = 0.034) or present smokers (p = 0.006) and had a significantly higher number of pack years (p < 0.001). Controls had higher prevalence of diabetes mellitus in advanced stadium (p < 0.001). AAA-patients had a significantly lower forced expiratory volume in 1 second (p = 0.003), a lower count of blood platelet (p = 0.030) and a higher creatinine level (p = 0.032). Multivariate analysis showed following independent associations with AAA: COPD (OR = 12.242; p = 0.002), CKD (OR = 5.655; p = 0.003), present smoking (OR = 4.141; p = 0.002), CAD (OR = 2.603; p = 0.020), diverticulosis (OR = 1.844; p = 0.075), and blood platelet count (OR = 0.994; p = 0.023). Conclusions: Our knowledge about the pathophysiology of AAA is still not sufficient. Deep understanding of the disease builds a basis for a future pharmacological therapy. Knowing all risk factors of this disease could help early detection of the AAA. Establishing a screening for AAA should be taken into consideration