Utility Of CT Scan Research Articles

What is the Diagnostic Utility of an Abdominal CT Scan in the Hospitalized Medical Patient With Nonspecific Abdominal Pain?

size in 271 adenomas, the detection rate of CTC was 94 of 158 (59.5%) for adenomas 2 to 5 mm in size, 55 of 61 (90.2%) for those 6 to 9 mm in size, and 44 of 52 (84.6%) for those at least 10 mm in size. Among adenomas measuring 6mm or more and pathologically considered precancerous, the detection rate of CTC was 88.4%. Conclusions: CTC is useful for detection of colon tumors, including cancers and including adenomas over 6 mm in size. This modality represents effective screening for colon cancer.

39 RESIDENTS FOR QUALITY IMPROVEMENT IN UROLOGY (RESQU): THREE YEAR EXPERIENCE WITH A RESIDENT-CENTERED QUALITY IMPROVEMENT INITIATIVE

collection; unlike the first (baseline) phase, the second and third rounds were preceded by collaborative QI interventions, including comparative performance feedback and dissemination of clinical guidelines for optimal radiographic staging. We then evaluated utilization of bone and CT scans across CaP risk strata, USQC practice locations, and before and after the QI interventions. RESULTS: We collected data for 858 men with CaP, including 375, 262, and 221 cases from phases 1, 2, and 3, respectively. Based on the D’Amico classification system, 44%, 39%, and 17% had low-, intermediate-, and high-risk cancers, respectively. Overall, 25% and 22% of patients underwent staging with a bone scan or CT scan ordered by a USQC urologist. USQC practices differed significantly in their baseline use of bone and CT scans among men with lowand intermediate-risk tumors (p 0.01), but not among men with high-risk cancers (p 0.7) Compared with baseline practice patterns (31% bone scans, 28% CT scans), urologists in USQC practices ordered significantly fewer bone and CT scans in the post-intervention second (23%, 21%) and third (16%, 13%) phases of data collection (p-values 0.01). Driving this trend was a significant reduction in use of these studies among patients with lowand intermediate-risk cancers (Figure, p-values 0.05); among low-risk patients, only one study was positive for metastases. CONCLUSIONS: Following collaborative feedback of baseline utilization and review of clinical guidelines, USQC urologists reduced variations in practice patterns and significantly improved adherence with recommended staging practices.

Clinical indications and utilization of 320-detector row CT in 2500 outpatients

Clinical indications and utilization patterns for 3963 CT scans on 2500 consecutive patents on a 320-detector row CT in an outpatient setting were retrospectively analyzed and compared with previously reported CT studies. The impact of the latest generation CT technology, including whole organ perfusion, on indications and utilization patterns during the study period was also assessed. The top five requested CT scan types were abdomen/pelvis, chest, head, sinuses, and coronary CT angiography. Indication and utilization rates were similar to prior studies for abdomen/pelvis, non-cardiac chest, and head CT scans. Abdominal pain and headaches were the most frequent indications for abdomen/pelvis and head CTs, respectively. The 7.3% cardiac CT scan utilization rate was not comparable to rates of up to 72% in self-referral outpatient settings. Whole organ volume CT imaging was utilized in 100% of coronary CT angiography and 22.7% of head CTs. The 320-row CT had fewer negative head and body CT findings as compared to prior reports. The availability of new technology, such as whole organ dynamic scans, appears to have influenced CT indications, utilization and finding rates with a decrease in negative brain and body results. Comparisons with previous outpatient CT studies were similar for multiple categories with the exception of cardiac CT utilization, which is heavily influenced by self-referral. Further study of outpatient imaging indications and utilization rates from multiple centers may benefit from a standardized categorization to improve understanding of the disparate outpatient imaging environment.

Radiation dose from CT scanning: can it be reduced?

Abstract CT has been used to save many patients’ lives and the demand for CT is still increasing. At the same time, there has been increasing concern of the probability of cancer induction by CT radiation. It is necessary for everyone involved in CT scanning, particularly physicians who have to communicate with patients when planning a CT scan, to have a basic knowledge of the CT radiation dose and its potential adverse effects. We have undertaken a systematic review of the literatures to document the radiation dose from CT, the lifetime cancer risk from CT exposure, CT dose parameters, the internationnal CT diagnostic reference levels, and the use and limitation of the CT effective dose. In addition, we conducted a brief survey of the use of CT scan in some university hospitals in Thailand and estimated current CT doses at these hospitals. Our review and survey suggests that CT scanning provides a great benefit in medicine but it also becomes the major source of X-ray exposure. Radiation doses from a CT scan are much higher than most conventional radiographic procedures. This raises concerns about the carcinogenic potentials. We encourage every CT unit to adhere to the International Guidelines of CT dose parameter references. Our preliminary survey from some university hospitals in Thailand revealed that CT radiation doses are within acceptable standard ranges. However, the justification for utilization of CT scans should also be required and monitored. The importance of adequate communication between attending physician and consulting radiologist is stressed.

Utility of CT Scan in Detection of Melamine - Associated Urinary Stones

To detail the utility of CT scan in detection of urinary stones induced by melamine tainted formula. A total of 1062 children fed with melamine-contaminated infant formula were screened for urinary stones in our institute from September through December 2008. Ultrasonography of the urinary tract system was performed in all these children. If the children with suspected stones or severe obstruction were presented after ultrasound examination, the multi-detector row CT urographic examination was advocated subsequently. Ultrasound examination in combination with multi-detector row CT urography could increase the diagnostic rate from 3.4% (36/1062) by ultrasound examination alone to 4.6% (49/1062). The specificity and sensitivity of the multi-detector row CT urographic examination is higher than ultrasonography.

1: Ultrasonography Evaluation for Appendicitis In Children: Can We Safely Reduce CT Scan Utilization?

Appendicitis is the most common pediatric condition requiring emergency surgery. Although CT scan is the most accurate diagnostic modality for this illness, the risks of radiation exposure are not ideal. This study assessed the impact of a radiology department protocol to increase the use of ultrasonography (US) over CT scan in the initial evaluation of suspected pediatric appendicitis. Retrospective chart review of pediatric emergency department patients undergoing evaluation of appendicitis. Charts before and after the implementation of the ultrasonography protocol (where US was used as the initial imaging modality whenever possible) were reviewed. Patient demographics, CT and US results were recorded for each group. T-test and test characteristics with 95% confidence intervals (CI) were calculated. The gold standard for appendicitis was pathology report; for negative evaluations, return visits for appendicitis within one week of evaluation were used. Sixty-two patients underwent radiographic evaluation for appendicitis before and fifty-two after the ultrasonography protocol was established. Mean age was 13.7 years before and 12.1 years after. There were 15 cases of appendicitis before (24.2%) and 19 cases after (36.5%; p = 0.016). There was a significant reduction in the use of CT scan (75.8% to 44.2%, p=0.0005) and increase in the use of ultrasonography (33.8% to 78.8%, p<0.05) after the ultrasonography protocol was implemented. For US, the false negative rate was 0.05 (95% CI 0.002-0.26) before and 0.07 (95% CI 0.01-0.24) after. There were no false positive ultrasonographys in either group. Overall length of stay was shorter for patients evaluated by US alone versus CT alone (mean 5 hrs 19 min versus 7 hrs 16 min, p <0.005). Implementing a protocol to increase the use of ultrasonography in assessing pediatric appendicitis reduced the number of CT scans performed without increasing the rate of false negative or false positive evaluations. Thus, the radiation exposure was reduced without compromising diagnostic efficacy.

Intravenous Iodinated Contrast Media Reactions

Iodinated contrast media agents are some of the most frequently utilized nontherapeutic drugs in hospitals and outpatient facilities today. From the 1980s to the 1990s, utilization of CT scanning increased by 800% with projected increase in CT procedures of 122% from 2002 to 2008.1 More than 62 million CT scans are performed every year in the United States, with more than 50% requiring intravenous (IV) iodinated contrast media.2

44 ROUTINE ABDOMINAL COMPUTER TOMOGRAPHY SCAN MAY RESULT IN UNNECESSARY RADIATION EXPOSURE OF CHILDREN PRESENTING WITH BLUNT ABDOMINAL TRAUMA AND MICROHEMATURIA

You have accessJournal of UrologyTrauma/Reconstruction: Trauma & Reconstructive Surgery I1 Apr 201044 ROUTINE ABDOMINAL COMPUTER TOMOGRAPHY SCAN MAY RESULT IN UNNECESSARY RADIATION EXPOSURE OF CHILDREN PRESENTING WITH BLUNT ABDOMINAL TRAUMA AND MICROHEMATURIA Miki Haifler, Orit Raz, Laurian Copel, Erez Lang, Helio Sipela, Yaniv Shilo, Ibrahim Abu Kishck, Baruch Klein, Arie Lindner, and Amnon Zisman Miki HaiflerMiki Haifler More articles by this author , Orit RazOrit Raz More articles by this author , Laurian CopelLaurian Copel More articles by this author , Erez LangErez Lang More articles by this author , Helio SipelaHelio Sipela More articles by this author , Yaniv ShiloYaniv Shilo More articles by this author , Ibrahim Abu KishckIbrahim Abu Kishck More articles by this author , Baruch KleinBaruch Klein More articles by this author , Arie LindnerArie Lindner More articles by this author , and Amnon ZismanAmnon Zisman More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.089AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES blunt renal trauma accounts for the majority of renal injuries in the pediatric population. abdominal CT scan is a valuable life-saving tool for the diagnosis of trauma in children but the inevitable radiation exposure remains a major disadvantage. The purpose of this study is to examine the yeild of abdominal CT scan while conservatively approaching pediatric renal trauma. METHODS from 1999 to 2007, 53 consecutive children were admitted for renal trauma, all had hematuria. the children were divided into two groups according to abdominal CT scan findings: group A: 29 children with hematuria and apparent anatomic renal injury, and group B: 24 with hematuria and no evidence for renal injury on imaging. RESULTS CT scan was able to totally discriminate between 6/29 patients who needed intervention versus those who did not 0/24, p=0.018. for all patients with microhematuria, regardless of imaging, none required blood transfusion and 31/33 (94%)were managed conservatively versus 16/20 (80%) with macrohematuria (p=0.121), representing 16.5 CT scans performed per one intervention in patients with microhematuria versus 4 ct scans per one intervention in patients with macrohematuria (ratio 3.9). no mortality was recorded in the entire cohort. one renal unit was lost in group A. multi-organ injury was recorded in 14 patients (48%) in group A versus 4 in group B (17%, p=0.016). CONCLUSIONS conservative treatment is afeasible approach in pediatric renal trauma at large. CT scan is able to accurately identify patients at risk for intervention. however, the yeild of abdominal CT in pediatric renal trauma is very low especially in patients presenting with microhematuria. ways should be found in order to cautiously limit the utilization of abdominal CT scan in children with microhematuria and blunt renal trauma in order to reduce radiation exposure. Beer Yaakov, Israel© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e18 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Miki Haifler More articles by this author Orit Raz More articles by this author Laurian Copel More articles by this author Erez Lang More articles by this author Helio Sipela More articles by this author Yaniv Shilo More articles by this author Ibrahim Abu Kishck More articles by this author Baruch Klein More articles by this author Arie Lindner More articles by this author Amnon Zisman More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Intermittent torsion of accessory hepatic lobe: An unusual cause of recurrent right upper quadrant pain

An accessory lobe of the liver is a rare congenital anomaly that can undergo torsion and present as an acute surgical emergency. It is rarely diagnosed preoperatively. We report the preoperative utility of CT scan and MRI in the diagnosis and surgical planning of a case of intermittent accessory hepatic lobe torsion.

Resource utilization and outcome at a university versus a community teaching hospital in tPA treated stroke patients: a retrospective cohort study

BackgroundComparing patterns of resource utilization between hospitals is often complicated by biases in community and patient populations. Stroke patients treated with tissue plasminogen activator (tPA) provide a particularly homogenous population for comparison because of strict eligibility criteria for treatment. We tested whether resource utilization would be similar in this homogenous population between two hospitals located in a single Midwestern US community by comparing use of diagnostic testing and associated outcomes following treatment with t-PA.MethodsMedical records from 206 consecutive intravenous t-PA-treated stroke patients from two teaching hospitals (one university, one community-based) were reviewed. Patient demographics, clinical characteristics and outcome were analyzed, as were the frequency of use of CT, MRI, MRA, echocardiography, angiography, and EEG.ResultsSeventy-nine and 127 stroke patients received t-PA at the university and community hospitals, respectively. The two patient populations were demographically similar. There were no differences in stroke severity. All outcomes were similar at both hospitals. Utilization of CT scans, and non-invasive carotid and cardiac imaging studies were similar at both hospitals; however, brain MR, TEE, and catheter angiography were used more frequently at the university hospital. EEG was obtained more often at the community hospital.ConclusionsUtilization of advanced brain imaging and invasive diagnostic testing was greater at the university hospital, but was not associated with improved clinical outcomes. This could not be explained on the basis of stroke severity or patient characteristics. This variation of practice suggests substantial opportunities exist to reduce costs and improve efficiency of diagnostic resource use as well as reduce patient exposure to risk from diagnostic procedures.

Are CT Scans Over-Utilized for the Diagnosis of Appendicitis?

Introduction: Acute appendicitis a challenging diagnosis to make for surgeons and emergency medicine physicians alike. It is by far the most common non-traumatic surgical emergency coming through the emergency departments. Over the years, CT scan has become an important adjunct diagnostic tool. Unfortunately, over utilization of CT scanning has been questioned since it increases time patients spend in the emergency department, subject patients to additional radiation, and increases healthcare costs.

Acute appendicitis: Is removal of a normal appendix still existing and can we reduce its rate?

Sir, I read with great interest the article written by Dr. Gamal Khairy[1] titled ‘Acute Appendicitis: Is Removal of a Normal Appendix Still Existing and Can We Reduce Its Rate?’ published in the Jul-Sep 2009 issue of the Saudi Journal of Gastroenterology. The author highlights the importance of clinically based diagnosis of acute appendicitis. The author comments about the futility of routine CT scan in the diagnosis of acute appendicitis based on the reports of 3 (5.5%) out of 54 patients of negative appendectomy who had undergone preoperative CT scan. Is it justified to comment on the diagnostic value of CT scan based on reports of only 3 patients? Literature has abundant studies having proponents as well as opponents regarding utility of CT scan for appendicitis. I agree with the author that clinical judgment is of paramount importance in the diagnosis and management of acute appendicitis even today and liberal use of CT scan should be strongly discouraged. The pitfalls of CT scan need to be understood,[2] and the potential radiation burden to the patient need not be overemphasized. However, I would like to mention here that imaging has a definite and well-established role in the diagnosis and management of appendicitis. A clinician will always face the dilemma of balancing between early appendectomy (to prevent perforation) and negative appendectomy. Laboratory investigations, though useful, are nonspecific. Here comes the role of definitive imaging studies. It is surprising that the article does not even mention about ultrasonography being done in any of the patients. Despite relatively low sensitivity of ultrasonography, it provides a very high specificity, which possibly could have addressed the author's primary concern of how to reduce negative appendectomy rates. Ultrasonography can be carried out with minimum delay and can yield pertinent and surgically relevant information like confirmation of diagnosis of appendicitis, status of inflamed appendix, location and orientation of appendix, presence or absence of any associated complications, adhesions, free fluid, etc., besides suggesting alternative diagnoses, which helps in appropriate surgical planning. Today, what we need is a proper diagnostic algorithm and triage of patients of appendicitis with regard to the choice of investigations. Dedicated appendiceal ultrasonography by an experienced sonologist should be the first imaging modality in suspected cases of acute appendicitis.[3,4] In case the sonographic study is equivocal or negative and the clinical suspicion is very strong, then the patient may undergo selective CT scan as per protocol or may even be taken up for surgery at the discretion of the treating surgeon.

Utility of double-contrast multidetector CT scans to assess cartilage thickness after tibial plafond fracture

The pathophysiology of post-traumatic osteoarthritis (PTOA) after intra-articular fractures is poorly understood. Pursuit of a better understanding of this disease is complicated by inability to accurately monitor its onset, progression and severity. Common radiographic methods used to assess PTOA do not provide sufficient image quality for precise cartilage measurements. Double-contrast MDCT is an alternative method that may be useful, since it produces high-quality images in normal ankles. The purpose of this study was to assess this technique's performance in assessing cartilage maintenance in ankles with an intra-articular fracture. Thirty-six tibial plafond fractures were followed over two years, with thirty-one MDCTs being obtained four months after injury, and twenty-two MDCTs after two years. Unfortunately, clinical results with this technique were unreliable due to pathology (presumed arthrofibrosis) and technical problems (pooling of contrast). The arthrofibrosis that developed in many patients inhibited proper joint access and contrast infiltration, although high-quality images were obtained in eleven patients. In this patient subset, in which focal regions of cartilage degeneration could be visualized, thickness could be measured with a high degree of fidelity. While thus useful in selected instances, double-contrast MDCT was too unreliable to be recommended to assess these particular types of injuries.

The Changing Presentation of Choledochal Cyst Disease: An Incidental Diagnosis

Background. Choledochal cysts are uncommon biliary lesions. Due to the evolution of imaging and laparoscopic surgery, we sought to describe our last 3 years experience with the presentation and management of choledochal cysts in adults. Methods. A retrospective review of a prospectively established database of adults who were managed for primary choledochal cyst disease between 2005 and 2008 was performed. Results. Between 8/2005 and 8/2008, 14 adults were managed for primary choledochal cyst disease. The average age was 41 years (range 17–86) and 79% were female. Presentations included biliary sepsis (3), pancreatitis (2), abdominal pain (3), or painless jaundice (1). Three patients had the cyst found during laparoscopic cholecystectomy, and two had an incidental finding after CT scan for an unrelated issue. The length of stay for those who had the cyst removed was 7.8 days (range 5–11). There were no operative or post-operative complications. Conclusions. Over the last 3 years 36% of our patients with choledochal cysts presented after incidental finding, either during a laparoscopic operation or after a CT scan for an unrelated problem. Increasing utilization of laparoscopy and CT scan for abdominal complaints has lead to a change in the pattern of presentation.

Endoscopic Ultrasound: A Diagnostic and Therapeutic Tool in Pancreatic Lesions

Purpose: Endoscopic ultrasound (EUS) has evolved from a simple imaging modality to one that can be used both for diagnostic and therapeutic purposes. The increasing utilization of CT scan of abdomen detects a number of silent pancreatic lesions - both cysts and masses. The ability of EUS to identify the pancreatic lesions that are too small to be identified by CT or MRI and to guide a needle both for biopsy or drainage, gives it a clear advantage over other imaging modalities in investigating pancreatic lesions. The aim of our study was to evaluate the outcome of EUS findings in patients with pancreatic abnormalities on CT or MRI and also to assess the utility of EUS as both a diagnostic and therapeutic modality. Methods: A chart review of all patients who underwent EUS at our hospital for suspected pancreatic pathology as found on CT or MRI of abdomen was conducted over a 3 year period. Pancreatic lesions found on EUS underwent a fine needle aspiration (FNA) and subsequent histopathological studies were followed up. Results: A total of 54 patients had EUS evaluation for pancreatic pathology. The study group comprised of 28 males and 26 females with a mean age of 56.9 years (range 27-79 years). Main indications of EUS in these cases were abnormal CT/MRI findings, suggestive of mass/cyst in the pancreas. *21 out of 54 cases had pancreatic cystic lesions. - 17 out of these cases were found to be simple cysts, of which 12 were drained and 5 cases could not be drained due to blood vessels surrounding the cyst or large cyst size. - 4 cases were found to be complex cysts, of which 3 were biopsied and only 1 was found to be malignant. *15 out of 54 cases showed solid mass lesions, of which 13 had FNA done and 8 were found to be malignant (4 adenocarcinoma; 1 neuroendocrine tumor and 3 were undeterminate). *10 out of 54 cases were evaluated for suspected pancreatic mass and were found to have chronic pancreatitis. *1 out of 54 cases was evaluated for MRI finding of annular pancreas, EUS confirmed this finding with no mass lesion. *7 patients had a completely normal EUS despite a suspected mass on CT/MRI study. Conclusion: EUS guided cystic drainage helped to resolve simple cysts and served as a diagnostic tool for complex pancreatic cysts in majority of the cases. EUS helped in the staging of solid pancreatic lesions and helped to ascertain the histopathological diagnosis. The possibility of using EUS for both diagnostic and therapeutic purpose gives it superiority over other imaging modalities like ultrasound/CT/MRI and MRCP. The disadvantages of EUS are that it needs a great deal of technical expertise, state of the art equipment and the need for IV sedation during the procedure.

Diagnostic Utility of CT Scan for Acute Headache

ED records for 364 children 2 to 5 years of age who presented to the Children’s National Medical Center ED, Washington, DC, between July 1, 2003, and June 30, 2006, with headache as their chief complaint, were examined to determine whether CT scans led to better acute management, justifying the risk of radiation.

Posterior shoulder dislocation associated with acromion fracture

We report a case involving a combination of posterior glenohumeral dislocation and acromion fracture in which the initial treating physician missed the shoulder dislocation. There are only two documented cases with a similar combination of injuries. A correct diagnosis of posterior dislocation is usually delayed due to subtle physical and radiological signs. Associated trivial injuries like acromion fracture may mask more significant injuries, which, if left untreated, may result in significant functional disability. The mechanism of injury, management and outcome in the present case is presented. The utility of CT scan in definitive diagnosis of posterior shoulder dislocation and identification of associated injuries is emphasized.

Hemorrhagic Complications of Ventriculostomy Placement: A Meta-Analysis

The reported intracerebral hemorrhage rate due to ventriculostomy placement varies widely. As studies emerge regarding alternative techniques of ventriculostomy placement, and placement by non-neurosurgeons, further definition of the true intracerebral hemorrhage rate associated with ventriculostomy is warranted. We performed a meta-analysis of the existing literature to further elucidate the incidence of intracerebral hemorrhage due to ventriculostomy. We performed an extensive literature search using Ovid MEDLINE and PubMed for relevant studies published after 1970. Only studies with more than 25 ventriculostomy procedures were included. Data were extracted regarding number of hemorrhages, clinically significant hemorrhages, and the use of routine post-ventriculostomy CT scanning. We performed subgroup analyses based on the use of routine post-ventriculostomy CT scanning. Chi-squared test was used to determine statistical significance. Overall, 102 hemorrhagic complications from 1,790 ventriculostomies were reported, a hemorrhage rate of 5.7%. Of the 102 hemorrhages, 11 were clinically significant (clinically significant hemorrhage rate = 0.61%). In studies that used routine post-placement CT scans, the hemorrhage rate was 10.06%, compared to a hemorrhage rate of 1.53% in studies in which routine CT scans were not performed (P < 0.001). Eight clinically significant hemorrhages (0.91%) were identified in the studies utilizing routine post-procedural CT scanning, compared to three clinically significant hemorrhages (0.33%) in studies without routine CT scans (P = 0.113). The overall hemorrhage risk associated with ventriculostomy placement based on the existing literature is 5.7%. Clinically significant hemorrhage due to ventriculostomy is less than 1%. Modifications of technique that might reduce hemorrhage risk, and the utility of routine post-procedural CT scanning, merit further investigation.

Dual energy computed tomography in tophaceous gout

Objective:To evaluate the potential utility of a dual energy CT (DECT) scan in assessing urate deposits among patients with tophaceous gout, and obtain computerised quantification of tophus volume in peripheral...

CT utilization: the emergency department perspective

CT scan utilization in the pediatric emergency department (ED) has dramatically increased in recent years. This likely reflects the improved diagnostic capability of CT, as well as its wider availability. However, the utility of CT is tempered by the high radiation exposure to patients as well as cost. In this review we will consider the magnitude of changes in CT use in the pediatric ED, and we will examine some of the driving forces behind these increases. In addition, we will consider strategies to limit growth in CT scan utilization or even result in reductions in CT use in the future. These strategies include better physician and patient education, application of existing clinical decision rules to reduce CT utilization and development of new rules, technical alterations in CT protocols to reduce per-exam exposures, use of alternative imaging modalities such as US and MRI that do not expose patients to ionizing radiation, and expanded use of clinical observation in place of immediate diagnostic imaging. Reform of liability laws might alleviate another driving force behind high CT utilization rates. Protocols must be designed to maximize patient safety by limiting radiation exposures while preserving rapid and accurate diagnosis of time-sensitive conditions.