CT dose optimization with model based iterative reconstruction

The aim of this thesis is to assess the feasibility of using model-based iterative reconstruction (MBIR) to develop new low-dose CT (computed tomography) protocols in the areas of neck, chest, and abdominal imaging without compromising diagnostic performance. Medical imaging has become the largest source of radiation exposure for humans other than natural background radiation. The availability of and improvements in diagnostic imaging have led to a sevenfold increase in the use of imaging over the past 30 years. This is especially true for CT, with a 7.8% annual increase in the use of CT from 1996 to 2010. The major concern associated with the widespread uptake of CT is the parallel increase in radiation exposure incurred by patients, and while the relationship of diagnostic radiation exposure to a quantifiable risk of cancer induction remains a controversial topic, physicians are beholden to keep radiation doses from diagnostic imaging as low as reasonably possible to limit the risk of radiation-induced cancer. We conducted preliminary phantom and cadaveric studies to examine the performance of MBIR at different radiation dose levels in the thorax and abdomen. Cadavers and phantoms provide a means of safely assessing new technologies and optimizing scan protocols prior to clinical validation. An anthropomorphic torso phantom and 5 human cadavers were scanned at varying radiation dose levels and images reconstructed using three different reconstruction techniques: filtered back projection, hybrid IR and MBIR. MBIR reduced image noise and improved image quality even in CT images acquired with a mean radiation dose reduction of 62%, compared with conventional dose studies reconstructed with hybrid IR, with lower levels of objective image noise, superior diagnostic acceptability and contrast resolution, and comparable subjective image noise and streak artifact scores. We subsequently performed clinical studies with the objectives of assessing MBIR as a tool for image quality improvement and radiation dose reduction in CT, and for the development of new low-dose carotid angiography, chest, and abdominopelvic CT protocols. We developed a low-dose carotid CTA protocol reconstructed with MBIR comparable to a conventional dose CTA protocol in terms of image quality and diagnostic accuracy while enabling a dose reduction of 49.6%. 20 patients were scanned using a split-dose technique with radiation dose divided into a low-dose acquisition reconstructed with MBIR and a conventional dose acquisition reconstructed with hybrid IR. Mean effective dose was significantly lower for the low-dose studies (1.84mSv versus 3.71mSv) and subjective image noise, contrast resolution, and spatial resolution were significantly higher for the low-dose studies. There was excellent agreement for stenosis grading accuracy between low- and conventional dose studies (Cohen κ = 0.806). A modified low-dose CT thorax protocol reconstructed with MBIR was also developed to monitor pulmonary disease progression in patients with cystic fibrosis with our low-dose protocol enabling the acquisition of a full-volume diagnostic quality chest CT at a dose equivalent to that of a chest radiograph (0.09±0.01mSv). Finally, we assessed the feasibility of low-dose abdominopelvic CT performed with MBIR as a radiation dose reduction strategy for imaging patients presenting with acute abdominal pain. A 74.7% mean radiation dose reduction was achieved with scans performed in the peri- and submillisievert range in patients of normal and low BMI, respectively, without compromising diagnostic performance. Dose reduction to the submillisievert range for patients with an elevated BMI was a challenge. The current era is extremely exciting in terms of radiation dose optimization in CT. This thesis is a demonstration of the potential for substantial reductions in radiation exposure, when the benefits of iterative reconstruction are combined with automated tube current modulation and other CT scanner technologies. The combination of all these hardware and software developments is now seeing major benefits for the patient and moving beyond the narrow aim of radiation exposure reduction to a complete change in practice, towards replacement of conventional radiography with low-dose CT, without any penalty for the patient in terms of radiation exposure

Low-Dose Abdominal CT for Evaluating Suspected Appendicitis in Adolescents and Young Adults Review of Evidence

Due to its excellent diagnostic performance, CT is the mainstay of diagnostic test in adults with suspected acute appendicitis in many countries. Although debatable, extensive epidemiological studies have suggested that CT radiation is carcinogenic, at least in children and adolescents. Setting aside the debate over the carcinogenic risk of CT radiation, the value of judicious use of CT radiation cannot be overstated for the diagnosis of appendicitis, considering that appendicitis is a very common disease, and that the vast majority of patients with suspected acute appendicitis are adolescents and young adults with average life expectancies. Given the accumulated evidence justifying the use of low-dose CT (LDCT) of only 2 mSv, there is no reasonable basis to insist on using radiation dose of multi-purpose abdominal CT for the diagnosis of appendicitis, particularly in adolescents and young adults. Published data strongly suggest that LDCT is comparable to conventional dose CT in terms of clinical outcomes and diagnostic performance. In this narrative review, we will discuss such evidence for reducing CT radiation in adolescents and young adults with suspected appendicitis.</p

충수염 의증 청소년 및 젊은 성인에서 2-mSv CT와 기존 선량 CT의 민감도 및 특이도: LOCAT의 사후 하위그룹 분석

학위논문(박사)--서울대학교 대학원 :융합과학기술대학원 융합과학부,2019. 8. 이경호.Introduction: To explore heterogeneity across patient or hospital characteristics in the diagnostic sensitivity and specificity of 2-mSv CT relative to conventional-dose CT (CDCT) in adolescents and young adults with suspected appendicitis. Methods: We used the per-protocol analysis set of a large randomized controlled noninferiority trial conducted between Dec 2013, and Aug 2016, comparing 2-mSv CT and CDCT (typically 7 mSv). The data included 2,773 patients (median age [interquartile range], 28 [21–35] years) and 160 radiologists from 20 hospitals. We tested for heterogeneity in sensitivity and specificity for the diagnosis of appendicitis across predefined subgroups by patient sex, body size, clinical risk scores for appendicitis, time of CT examination (i.e., working hours [typically 08:00–17:00 of working days] vs. after hours), CT machines, radiologists experience, previous site experience in 2-mSv CT, and site practice volume. We drew forest plots and tested for additive or multiplicative treatment-by-subgroup interaction on sensitivity and specificity. Results: The 95% CIs for the between-group differences, particularly for sensitivity, were wide due to small sizes (< 200) for the subgroups of extreme body sizes, high clinical risk score for appendicitis, newer CT machines, hospital with prior experience in 2-mSv CT, and hospitals with small appendectomy volume. Otherwise, the 95% CIs in most subgroups contained the previously reported overall between-group differences as well as null hypothesis value (i.e., 0). There was no significant additive or multiplicative interaction for either sensitivity or specificity. Conclusions: We found no notable subgroup heterogeneity, which implies that 2-mSv CT can replace CDCT in diverse populations. Further studies are needed for the populations for which our subgroups were small.서론: 본 연구는 충수염 의증 청소년 및 젊은 성인에서 기존 CT와 비교하여 2-mSv CT의 진단 민감도 및 특이도에서 환자 또는 병원의 특성에 따른 이질성이 있는지를 탐색하는 연구임. 방법: 본 연구는 2013년 12월에서 2016년 8월 사이에 15–44세의 환자에서 2-mSv CT와 기존 선량 CT (일반적으로 7 mSv)를 비교한 대규모 비열등성 무작위배정 임상시험의 프로토콜 별 분석세트를 사용함. 본 연구에는 20개 병원에서 2,773명의 환자 (중앙값 연령 [사분위수 범위], 28 [21–35]세)가 포함되었으며, 160명의 판독의가 참여함. 환자의 성별, 신체 크기, 충수염에 대한 임상 위험 점수, CT 검사시간 (일과시간 [근무일 기준 오전 8시부터 오후5시] 또는 일과시간 이후), CT 장비, 판독의의 경험정도, 2-mSv CT에 대한 이전 경험 여부, 그리고 병원의 임상규모 등의 사전 정의된 하위 그룹에서 충수염 진단을 위한 민감도 및 특이도의 이질성을 테스트함. 두 군의 차이를 숲그림으로 제시하고, 민감도와 특이도에 대한 덧셈 및 곱셈 상호작용을 테스트함. 결과: 많이 날씬하거나 뚱뚱한 경우, 충수염 염증 반응 점수가 높은 경우, 최신 CT 기기를 사용한 경우, 2-mSV CT 의 이전 경험이 있는 병원, 그리고 충수절제술 규모가 작은 병원의 경우 등 특정 하위 그룹은 작은 크기 (< 200)로 인해 민감도에 대한 95 % 신뢰구간이 넓었음. 그 외, 대부분의 하위 그룹에서 그룹 간 차이에 대한 95 % 신뢰구간은 이전 보고된 전체 그룹 간 차이 및 귀무 가설 값 (즉, 0)을 포함하였음. 2-mSv CT 군과 기존 선량 CT 군 간에 민감도 및 특이도에서 덧셈 또는 곱셈 상호작용을 보이는 하위 그룹은 없었음. 결론: 충수염 의증 청소년과 젊은 성인에서 2-mSv CT와 기존 선량 CT 간에 민감도와 특이도에서 이질성을 보이는 하위그룹은 없었음. 이는 2-mSv CT가 다양한 집단에서 기존 선량 CT를 대체할 수 있음을 의미함. 다만, 본 연구에서 작은 크기를 가진 일부 하위 그룹에 대해서는 추가적인 연구가 필요함.INTRODUCTION 1 Motivations of LOCAT 1 Purposes of LOCAT 3 Motivations of Dissertation Research 4 Purposes of Dissertation Research 5 BACKGROUND 7 Epidemiology of Appendicitis and CT utilization 7 Imaging Utilization 7 Popularity of CT 8 CT Radiation 9 Radiation Dose Level 10 Typical Radiation Dose for Multi-purpose Abdomen CT 10 Typical Radiation Dose for Appendiceal CT 11 Low Doses Explored in Research Settings 12 Carcinogenic Risk Associated with CT Radiation 12 Controversy 13 ALARA Principle 14 Efficacy and Effectiveness of LDCT Compared to CDCT 15 Clinical Outcome 19 Diagnostic Performance 20 Inter-observer Agreement 21 Differentiation between Complicated vs. Uncomplicated Appendicitis 22 Image Quality 24 Visualization of the Appendix 24 Alternative Diagnoses 25 Step-wise Multimodal Diagnostic Approach Incorporating LDCT 27 Patient Subgroups Less Benefited from LDCT 27 Selective Utilization of LDCT 29 Additional Imaging Test(s) Following LDCT 30 Imaging Techniques for LDCT for Suspected Appendicitis 31 Intravenous Contrast Enhancement 31 Contrast-enhancement Phase 31 Enteric Contrast 32 Anatomical Coverage 32 Tube Current 33 Tube Potential 34 Iterative Reconstruction 34 Image Reconstruction Thickness 35 Coronal Reformation 35 Sliding-Slab Averaging Technique 36 Image Interpretation and Reporting for LDCT 37 Diagnostic Criteria for Appendicitis 37 Structured Reporting 38 Other Practical Issues in Implementing LDCT 39 Dedicated Protocol for Appendiceal CT 40 Education for Referring Physicians and Surgeons 41 Education for Radiologists 42 Dose Calibration and Monitoring 43 MATERIALS AND METHODS 47 Study Overview 47 Practice Setting 48 Pre-registration Procedures 48 Study Organization and Site Recruitment 49 Site Activation 50 Patients 51 Eligibility Criteria 54 Clinical Suspicion for Appendicitis 55 The Need for CT Examination 55 Generalizability 56 Representativeness of Study Sample 57 Withdrawal Criteria 58 Randomization 58 Index Test 59 CT Image Acquisition and Archiving 66 Radiation Doses 69 Record of Modulated Radiation Dose 71 Target Median DLP Values for the 2-mSv CT and CDCT groups 71 Calibration of Radiation Doses 72 Estimation of Carcinogenic Risk Associated with CT Examination 74 Image Interpretation 75 Radiologists and CT Reports 76 Radiologist Training 78 Considerations Regarding Technical Advantages over Previous Studies 79 Image Submission 80 Co-intervention 81 Additional Imaging 82 General Treatment Guidelines 82 Follow-up 84 Endpoints in LOCAT 85 Primary Endpoint 86 Secondary Endpoints 86 Considerations for NAR and APR 89 Changes in Endpoints 89 Reference Standards 91 Overview of Reference Standards 91 Definition of Acute Appendicitis 92 Mild or Early Acute Appendicitis 92 Appendiceal Diverticulitis 93 Cases of Delayed Appendectomy 93 Periappendicitis 93 Definition of Appendiceal Perforation 94 Reporting AEs 95 Definition of AE 96 Definition of SAE 97 AE Characteristics 97 Grade 98 Expected/Unexpected AEs 98 Attribution 98 Individual Symptoms vs. Single Diagnosis 99 Who Should Report AEs 99 How to Report AEs 99 Follow-up for AEs 100 Ethical Considerations 100 Ethics and Responsibility 100 Informed Consent Form 101 Data Security and Participant Confidentiality 101 Early Stopping Rules in LOCAT 101 Data Management 102 Case Report Forms 103 Monitoring Participant Accrual 103 Monitoring Data Quality 103 Data and Safety Monitoring Board 105 Statistical Analysis 105 Considerations for Primary Endpoint 105 Analysis Plans 107 Sample Size 108 Sample Size Considerations 108 Final Sample Size 110 Rationale for the Noninferiority Margin 111 Reported NARs Following Preoperative CT 111 Reported NARs in Patients Without Preoperative CT 112 Sample Size Considerations on APR 113 Subgroup Analyses for APR and NAR 114 Subgroup Analyses for Diagnostic Performance 116 RESULTS 119 Patient Characteristics 119 Overall Diagnostic Performance 123 Subgroups of Limited Comparison 123 Between-group Differences for Subgroups 123 Heterogeneity 131 DISCUSSION 132 CONCLUSION 139 REFERENCES 140 APPENDIX 164 Abstract in Korean 176Docto

Uncomplicated acute appendicitis – towards optimization of diagnostics, antibiotic management, and treatment costs

Acute appendicitis is the most common reason for acute abdominal pain, currently known to present in two different forms: uncomplicated and complicated acute appendicitis. This difference in appendicitis severity between these two forms can be quite accurately differentiated prior to treatment assessment using computed tomography (CT) imaging. Complicated acute appendicitis most often requires emergency appendectomy. However, recent accumulating evidence has shown antibiotic treatment to be a safe and feasible treatment alternative for uncomplicated acute appendicitis. Furthermore, in uncomplicated acute appendicitis, the overall treatment costs of antibiotics at short-term follow-up are lower compared to surgery. The main aim of this thesis was to evaluate oral (p.o.) antibiotic monotherapy as a first-line treatment for CT-confirmed uncomplicated acute appendicitis by comparing p.o. antibiotic monotherapy to a combination of intravenous (i.v.) followed by p.o. antibiotics in a randomized multicenter non-inferiority clinical trial (APPAC II). The second aim of this study evaluated the overall costs of surgical and antibiotic treatment for uncomplicated acute appendicitis at long-term follow-up of the APPAC randomized controlled trial (RCT) comparing antibiotics with appendectomy. The third aim of this study was to determine whether the radiation dose of the diagnostic CT imaging could be significantly lowered without compromising diagnostic accuracy by using low-dose CT imaging. In the treatment of CT-confirmed uncomplicated acute appendicitis, p.o. antibiotic monotherapy had similar clinical treatment efficacy as a combination of i.v. and p.o. antibiotics with 1-year success rates of 70.2% and 73.8%, respectively. At 5-year follow-up antibiotic treatment resulted in significantly lower overall costs compared with appendectomy. The accuracy of low-dose CT and standard CT was comparable in diagnosing acute appendicitis as well as in differentiating uncomplicated and complicated acute appendicitis. The low-dose CT was associated with a significant radiation dose reduction compared to standard-dose CT.Komplisoitumaton akuutti umpilisäketulehdus – Kohti diagnostiikan, antibioottihoidon ja kustannusten optimointia Akuutti umpilisäketulehdus eli appendisiitti on yleisin akuutin vatsakivun syy. Akuuttia appendisiittia on kahta eri muotoa: lievempi komplisoitumaton ja vaikeampi komplisoitunut akuutti appendisiitti. Nykyään nämä kaksi eri muotoa voidaan erottaa toisistaan tarkasti jo ennen hoidon määrittämistä tietokonetomografiakuvauksen (TT) avulla. Komplisoitunut akuutti appendisiitti vaatii tavanomaisesti välitöntä leikkaushoitoa. Viimeaikaisten tutkimustulosten mukaan antibioottihoito on osoitettu turvalliseksi ja käyttökelpoiseksi hoitovaihtoehdoksi komplisoitumattomassa appendisiitissa. Käytettävissä olevien lyhyen seurantavälin tutkimustulosten mukaan komplisoitumattoman appendisiitin hoidosta antibiootilla aiheutuu vähemmän kustannuksia verrattuna leikkaushoitoon. Tämän väitöskirjatyön tarkoituksena oli tutkia suun kautta otettavaa antibioottihoitoa ensilinjan hoitona komplisoitumattomassa akuutissa appendisiitissa vertaamalla tablettimuotoisen antibioottihoidon tehoa suonensisäisen ja suun kautta otettavan antibioottihoidon yhdistelmään satunnaistetussa non-inferioriteetti-monikeskustutkimuksessa (APPAC II). Lisäksi tutkimme antibioottihoidon ja leikkaushoidon kokonaiskustannuksia pitkän aikavälin seurannassa. Arvioimme myös, voiko appendisiittin diagnostiikassa käytetyn TT-kuvauksen potilaalle aiheuttamaa säderasitusta pienentää heikentämättä kuvauksen diagnostista tarkkuutta. Komplisoitumattoman akuutin appendisiitin hoidossa tablettimuotoinen antibioottihoito oli kliinisesti yhtä tehokas kuin yhdistelmäantibioottihoito, hoidon onnistuessa vuoden seurantajakson aikana 70.2 %:lla tablettimuotoista ja 73.8 %:lla yhdistelmäantibioottihoitoa saaneilla. Viiden vuoden seurannassa antibioottihoidosta aiheutui tilastollisesti merkitsevästi vähemmän kustannuksia verrattuna leikkaushoitoon. Matala-annoksisen ja standardiannos-TT-kuvantamisen tarkkuus oli toisiaan vastaava sekä akuutin appendisiitin diagnosoinnissa että komplisoitumattoman ja komplisoituneen akuutin appendisiitin erottamisessa. Matala-annoskuvantamisesta aiheutui tilastollisesti merkitsevä sädeannoksen pieneneminen verrattuna standardiannoksiseen TT-kuvantamiseen

Small bowel obstruction and toxicity of a new model of adhesion prevention

Abstract Background: Small bowel obstruction (SBO) is a common surgical diagnosis. If no signs of strangulation are evident, the majority of the patients can be conservatively managed. Approximately one third of the patients need surgical treatment and there is a need for early parameters that can predict operative intervention. The etiology of SBO in most cases is postoperative abdominal adhesions. Laparoscopic surgery generates less surgical trauma and thereby possibly less adhesion formation and subsequent decreased risk of SBO. The burden of postoperative adhesions is substantial and there is a need for an adhesion preventive agent that can be used in different clinical situations and reduce the clinical complications caused by adhesions, ie SBO, infertility and chronic abdominal pain. Previous experimental studies have reported promising anti adhesive effect of intraabdominally installed differently charged polypeptides in different clinical settings. However, there was observed toxicity of the cationic polypeptide when administered alone. Aims/methods: The aims of the retrospective clinical studies were to identify early parameters predicting surgical intervention in patients with SBO (I) and to determine whether there is a difference in the incidence of SBO after open versus laparoscopic surgery for suspected appendicitis (II). In the experimental studies the aims were to establish the lowest anti adhesive dose of α-polylysine (PL) in combination with polyglutamate (PG) and determine the toxic dose of α-PL (III), to investigate the possible anti adhesive effect of another four cationic polypeptides in combination with PG (IV). Furthermore, explore the mechanism of toxicity as well as the biodistribution of α-PL, alone or in combination with PG, after intravenous and intraperitoneal administration (V). Results/conclusions: 109 patients were included, 65 were conservatively managed and 44 were surgically treated. We identified five parameters, possible to retrieve within 4 hours from hospital admission, that were more frequent in the patients that were surgically treated for SBO. These parameters can possibly be used to advance the selection of patients for operation (I). The incidence of SBO after open and laparoscopic surgery for suspected appendicitis was low in both groups, 1% (24/2333) and 0,4% (10/2372) respectively. The difference was minor but significant, favoring the laparoscopic approach (II). We could show that the anti adhesive effect of α-PL/PG was dose dependent and the lowest effective dose for α-PL was established. The toxic dose of α-PL was determined and the gap between the lowest effective dose and the toxic dose is probably too narrow (III). All four alternative cationic polypeptides (polyarginine, lactoferrin, lysozyme,ε-PL) investigated in the fourth study showed anti adhesive effect. ε-PL, another isoform of PL, was superior to the other three and showed less toxicity than α-PL (IV). High doses of intravenous α-PL caused a damage to endothelial cells with subsequent edema and extravasation of blood in lung and liver. The biodistribution and accumulation of α-PL and α-PL/PG in blood and organs is lower and slower after intraperitoneal than intravenous administration (V)

Improving the assessment process for patients presenting with acute (non-traumatic) abdominal pain to the general surgery department.

Background Abdominal pain is a very common but also challenging presentation to general surgery. A number of implementations have been introduced to improve the diagnostic process. These include: ED 4-6 hour targets, acute surgical admission units and better access to additional imaging (mainly CT scan). Regardless of these implementations, there seems to be ongoing inefficiency within the diagnostic process, with subjective observation of long transit times between presentation and start of treatment. Improving the diagnostic process and the use of imaging for this patient group will result in better use of hospital resources and improved patient care. Section 1 Aim To evaluate the current process of how patients presenting with abdominal pain to the general surgery department are assessed. Methods This section consists of 4 separate studies evaluating the number of admissions, diagnoses, the use of imaging and access to theatre. Conclusion Over the last decade a significant increase was seen in the number of patients admitted with a non-surgical diagnosis (constipation, gastroenteritis and non-specific abdominal pain). Also, CT scans were performed more frequently. This did, however, not affect the negative appendicectomy rate. Furthermore, according to an expert panel, approximately one-fifth of the scans was considered not indicated. These findings highlighted the areas for improvement in the diagnostic process for patients presenting with acute abdominal pain. Section 2 Aim To identify the current evidence of diagnostic pathways for patients presenting acutely with abdominal pain. Methods A systematic review was performed including all studies that described an algorithm for assessing patients presenting with acute, nontraumatic, abdominal pain Conclusion The systematic review found that 10 studies described a diagnostic pathway for diagnosing patients with abdominal pain. All pathways supported routine imaging (ultrasound and/or CT scan). However, none of the studies reported a reduction in complication rate, mortality or length of stay. Section 3 Aim The first step in this section was to identify whether registrars could accurately identify the urgent from the non-urgent patient presenting with abdominal pain. The second step was the implementation of a quality improvement initiative aiming to encourage early discharge for patients presenting with non-surgical abdominal pain and to reduce use of imaging for this patient group. Methods This section contains of two prospective cohort studies. Conclusion The first step showed that registrars could accurately identify the urgent from the non-urgent patient presenting with abdominal pain. This enabled us to introduce the second step, which was the implementation of a quality improvement initiative. In this study a significant increase in early discharges for patients presenting with non-surgical abdominal pain was observed and the use of imaging for this patient group significantly decreased. Representation and complication rates remained unchanged. Overall conclusions This PhD highlights the problems in the assessment process for patients presenting with abdominal pain. When the assessment process can be optimised by implementing the quality improvement initiative,limited health care resources are used more wisely. This has obvious cost implications, but should also result in increased focus on patients with acute surgical pathology and improve their outcomes

Akuutin umpilisäketulehduksen diagnostiikka : diagnostinen pisteytys ja leikkausta edeltävän viiveen merkitys

Background and aims: Diagnostic scoring is a method for stratifying patients according to the probability of appendicitis, and therefore works as an excellent basis for a diagnostic algorithm. This study aimed at developing a new diagnostic score, the Adult Appendicitis Score (AAS), and validating its routine use as an integral part of a new diagnostic algorithm. Diagnostic accuracy of the imaging studies depends on the pre-test probability of the disease. This study aimed to assess how accurate the imaging was in various AAS-stratified pre-test probability groups. The effect of in-hospital delay on the risk of perforation is controversial. The research in this thesis aimed to further clarify the matter. Patients and methods: The study enrolled 1737 patients with acute right lower quadrant abdominal pain. The first data collection of 829 patients was used to develop the AAS and compare it with two previously published scores as well as with the clinical assessment. The validation study of AAS enrolled 908 patients in two university hospitals. The negative appendectomy rate was compared between the first and second patient cohort. Patients that had diagnostic imaging were stratified into three probability-of-appendicitis groups according to the AAS, and the diagnostic accuracy of ultrasound (US) and computed tomography (CT) were compared between the score groups. To find the best marker to detect pre-hospital perforations, laboratory results and two previously published diagnostic scores were analyzed. The effects of total duration of symptoms, pre-hospital delay, and in-hospital delay on the risk of perforation were analyzed. Results: After the AAS was developed and incorporated into a new diagnostic algorithm the negative appendectomy rate decreased from 18.2% to 8.2%. With a specificity of 93%, the AAS stratified half of all patients with appendicitis into the high-probability group. The probability of appendicitis was only 7% for the low-probability group. The AAS outperformed both the clinical assessment and two previously published scores. The diagnostic accuracy of imaging depended on the pre-test probability of appendicitis. When compared to the two other groups allocated by the AAS, in the low-probability group a positive CT and US findings yielded lower post-test probability for appendicitis. More false than true positive US results were found in the low-probability group. C-reactive protein (CRP) was the best marker for pre-hospital perforation. For patients with CRP values less than 99 mg/l longer in-hospital delay increased the perforation risk whereas the duration of pre-hospital delay showed no difference between patients with uncomplicated and complicated appendicitis. For patients with CRP values 99 mg/l or more, the in-hospital delay did not increase the perforation risk. Conclusions: The AAS provides an accurate method to stratify patients according to their probability of appendicitis. After the score was implemented into clinical routine, it led to a dramatic reduction in the negative appendectomy rates. When the AAS stratifies the patient to have a low probability of appendicitis, the benefits of imaging are questionable. False positive imaging results can even induce negative appendectomies. Most perforations in acute appendicitis occur as pre-hospital events. However, some of the perforations can be avoided by minimizing the in-hospital delay.Akuutti umpilisäketulehdus on tavallinen äkillisen vatsakivun syy. Vaikka umpilisäketulehduksen oireet ovat hyvin tunnettuja, tehdään edelleen myös turhia leikkauspäätöksiä. Uuden, väitöstutkimuksen yhteydessä kehitetyn, diagnostisen pisteytyksen käyttöönoton havaittiin vähentävän merkittävästi turhien umpilisäkepoistojen osuutta. LL Henna Sammalkorven tuoreessa väitöstutkimuksessa kehitettiin uusi aikuisten potilaiden tutkimisessa hyödynnettävä diagnostinen pisteytys, Adult Appendicitis Score. Pisteytyksellä potilaat, joilla epäillään umpilisäketulehdusta, jaotellaan kolmeen ryhmään umpilisäketulehduksen todennäköisyyden mukaan. Uuden pisteytyksen kehittämistä varten prospektiivisesti kerätty aineisto sisälsi 829 Meilahden sairaalassa umpilisäkkeen tulehduksen epäilyn vuoksi tutkittua potilasta. Aiempaa tarkempi pisteytys luotiin analysoimalla potilaiden oireita, tutkimuslöydöksiä ja laboratoriokoevastauksia. Uusi pisteytys oli tarkempi kuin päivystävien kirurgien arvio tai kumpikaan vertailussa mukana olleista aiemmin julkaistusta pisteytyksistä. Pisteytys on otettu rutiinikäyttöön osana uutta umpilisäkkeen tulehduksen diagnostista ohjeistusta Meilahden sairaalassa. Pisteytyksen käytän vaikutusta diagnostiikan tarkkuuteen tutkittiin 908 potilaan aineistossa Meilahdessa ja Kuopion Yliopistollisessa Sairalassa. Ennen uuden pisteytyksen käyttöönottoa 18,2 prosentissa Meilahden sairaalassa umpilisäkkeen tulehduksen epäilyn vuoksi tehdyissä leikkauksissa umpilisäke ei ollut tulehtunut. Uuden pisteytyksen käyttöönoton jälkeen luku laski 8,2 prosenttiin , Henna Sammalkorpi kuvaa tilannetta. Uuden pisteytyksen ohella tutkimuksessa selvitettiin sairaalaan saapumisen ja umpilisäkkeen poiston välisen aikavälin vaikutusta puhkeamariskiin. Tutkimuksessaan LL Henna Sammalkorpi havaitsi, että umpilisäkkeen puhkeaman todennäköisyyttä parhaiten kuvaava muuttuja on C-reaktiivinen proteiini, CRP. Potilailla, joiden CRP oli yli 99 jo sairaalaan tullessa, ei sairaalassa aiheutunut viive lisännyt puhkeaman todennäköisyyttä, sillä umpilisäke oli todennäköisimmin jo puhjennut ennen sairaalaan tuloa. Niillä potilaista, joiden CRP oli alle 99 sairaalassa aiheutunut viive lisäsi puhkeamariskiä. Mikäli sairaalassaoloaika ennen leikkausta kasvoi alle 6 tunnista yli 12 tuntiin, puhkeamariski kaksinkertaistui. Näin ollen osalla potilaista puhkeama voidaan välttää tarjoamalla potilaille viivytyksetöntä diagnostiikkaa ja hoitoa

Diseases of the Abdomen and Pelvis 2018-2021: Diagnostic Imaging - IDKD Book

Gastrointestinal disease; PET/CT; Radiology; X-ray; IDKD; Davo