MRI pediatric appendicitis

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1 Disclosures MRI pediatric appendicitis Brooke Lampl Cleveland Clinic Imaging Institute Section of Pediatric Radiology I have nothing to disclose. Objectives Discuss imaging choices in the evaluation of pediatric appendicitis. Demonstrate the utility of MRI in evaluation of pediatric patients with right lower quadrant pain. Discuss the diagnostic criteria for positive cases of appendicitis on MR imaging. What is the sensitivity and specificity of MRI in the evaluation of appendicitis? A. Similar to that of US B. Similar to that of CT C. Better than US or CT D. Not yet evaluated, too new a method What is a major advantage to the evaluation of appendicitis with MRI? A. Faster diagnosis B. Length of study C. Visualization of the entire appendix D. Operator dependency Clinical presentation and current evaluation of acute appendicitis 1

2 Appendicitis Most common atraumatic surgical disorder in children > 2 years Diagnosed in 1 8 % of children presenting to the ED with acute abdominal pain Incidence of 1 2 / 10,000 between birth and 4 yrs Incidence of 25 /10,000 between yrs Appendicitis Clinical Presentation Classic Pain pattern: Peri umbilical pain and nausea with subsequent right lower quadrant pain, fever and vomiting Seen in 50% adults Much less common in pediatrics Fever 4% of children Temp >38 when symptoms < 24 hrs 64% of children Temp >38 when symptoms > 24 hrs Appendicitis: Non specific signs and symptoms Misdiagnosis rate of >70 % in children < 3 yrs of age Perforation rate near 100 %, in children < 3 yrs of age Misdiagnosis rate of % in pre school age children Misdiagnosis rate of % in teens 28% of children are admitted to the hospital with an incorrect diagnosis Rothrock, et al Annals of Emergency Medicine 2000 Appendicitis: Child <2 years Symptoms Vomiting 85 90% Pain 35 75% Diarrhea 20 45% Fever 40 60% Irritability 35 40% Grunting respirations 10 25% Cough or rhinitis 40% Temp > 37 C % Diffuse abdominal pain 55 90% Localized RLQ pain < 50% Current choices in the evaluation of pediatric appendicitis Right lower quadrant US CT abdomen and pelvis with contrast (IV and/or oral) MRI abdomen and pelvis Choice 1: Ultrasound Benefits: availability, portability, low cost, and lack of ionizing radiation. Limitations: operator dependency, relative ineffectiveness in overweight/obese patients, and relative ineffectiveness in imaging the retrocecal appendix. Sensitivity and specificity of ultrasound have been reported at 87 95% and 85 98% respectively. 2

3 1986: Radiology Puylaert performed graded compression sonography on 60 patients with clinical signs of acute appendicitis. 25/28 (89%) with surgically proven appendicitis, she found the inflamed appendix by US 1990: Radiology Vignault does a prospective study to evaluate US diagnosis of appendicitis in children. 70 patients with clinically suspected appendicitis 35 called positive by US 31/35 confirmed at surgery and pathology 4/35 observed and resolved 17/70 patients positive for other diagnoses Sensitivity of 94%, Specificity of 89%, Accuracy of 91% Imaging findings in US appendicitis Appendiceal diameter >6 mm % Target sign with 5 concentric layers 50% Diffuse hypoechogenicity (necrosis of submucosa) +/ Diffuse hypoechogenicity with posterior enhancement (pus) Distension or obstruction of the appendiceal lumen 50% High echogenicity surrounding the appendix % Appendicolith % Pericecal free fluid < 5% Without compression With compression 3

4 Appendicitis: Ultrasound Initially 2 large studies (>5,000 children) Sensitivity % Specificity 97 98% Other studies Sensitivity 80% Specificity 86% User dependent Choice 2: Computed Tomography Benefits: available, fast, highly sensitive and specific Sensitivity and specificity: 95 97% and 94 97% respectively. Limitations: radiation. Because of ionizing radiation, many are trying to find alternative ways to image the appendix Appendix not visualized in 35 50% of normals Appendix not visualized in 10% of patients with appendicitis Obesity, abdominal wall rigidity, uncooperative children, atypical location, less experienced examiners CT Appendicitis: History 1997 Radiology: Rao, et al. Helical CT technique for the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination 100 patients enteric contrast, dedicated thin section CT of the RLQ sensitivity of 100% specificity of 95% positive predictive value of 97% negative predictive value of 100% Appendicitis: CT Rao, et al Sensitivity and Specificity of the Individual CT Signs of Appendicitis: Experience with 200 Helical Appendiceal CT Examinations fat stranding (100%, 80%) enlarged (>6 mm) unopacified appendix (93%, 100%) focal cecal apical thickening (69%, 100%) cecal bar (10%, 100%) adenopathy (62%, 66%) extraluminal air (8%, 97%) appendolith(s) (44%, 100%) phlegmon (7%, 99%) arrowhead sign (23%, 100%) ileal (3%, 86%) or sigmoid (3%, 95%) wall thickening paracolic gutter fluid (18%, 86%) diffuse cecal wall thickening (0%, 91%) abscess (11%, 100%) 4

5 Appendicitis: Boston Children Protocol 1999 Pena, et al. Ultrasonography and Limited Computed Tomography in the Diagnosis and Management of Appendicitis in Children Suspected appendicitis N=177 USG N= 139 Home N=4 Operating room N=34 4/34 false positives Home N=11 1 false negative OR N=20 CT scan N=108 OR N=31 3 false positive Home N=52 Observe N=25 1 false negative Boston Children Protocol 1999 Ultrasonography, N = 139 Went to Operating Room for Appendectomy, n = 20 Discharged Home, n = 11 A normal appendix was identified by ultrasonography in 2 of 83 (2.4%) patients without appendicitis Went on to be evaluated with CT, n = % of patients needed CT after their ultrasounds Pena, et al 1999 Why try Ultrasound? Estimated Risks of Radiation Induced Fatal Cancer from Pediatric CT Brenner, et al AJR 2001 Computed Tomography an Increasing Source of Radiation Exposure Brenner, Hall, NEJM 2007 The situation is even clearer for children, who are at greater risk than adult from a given dose of radiation both because they are inherently more radiosensitive and because they have more remaining years of life during which a radiation induced cancer could develop. How then should we image children? Develop an imaging strategy! Younger age increased risk per unit dose 5

6 Imaging Strategy 14 year old with RLQ pain Pena conducted a study in 2004 in Pediatrics stratifying patients by low, medium and high risk and determining evaluation The number of US followed by CT was decreased in these groups based on clinical stratification... And what about MRI? Nonvisualization of the appendix A common problem Stewart et al. looked at prevalence of appendicitis in patients with nonvisualization on US 260/400 had nonvisualization of the appendix (65%) 14 of those had appendicitis (5.38%) So let s save radiation. Let s try MRI! US demonstrated sensitivity of 73.3%, specificity 98.5% 15 year old with RLQ pain 6

7 Choice 3: Magnetic Resonance Imaging Useful in pediatric cases where appendicitis is clinically suspected and the ultrasound is equivocal or the appendix cannot be identified. Advantages: a lack of ionizing radiation, and multi sequence, multiplanar images, can see the entire appendix Disadvantages: numerous artifacts, length of study, availability and cost. Already in use in pregnancy and adults MRI 2004 MRI for Clinically Suspected Appendicitis During Pregnancy 2005 Nitta, et al. MR imaging of the normal appendix and acute appendicitis 2009, Cobben, et al. A simple MRI protocol in patients with clinically suspected appendicitis: results in 138 patients and effect on outcome of appendectomy sensitivity 100% specificity 99% October 1998 AJR Takes children with positive appendicitis by US into the MR scanner to evaluate appearance Axial T1 Axial and coronal T2 Axial Fat sat STIR 7

8 Findings Could see the entire appendix in 100% of cases (on US only could see the entire appendix in 10%) MR imaging showed acute appendicitis in 100% of cases Blind ending, tubular structure Fluid filled lumen (T2 bright) Hypointense wall on T1 and mildly hyperintense on T2 due to edema T2 mildly hyperintense periappendiceal tissue Intraluminal round structure without signal on any sequence appendicolith in 20% June 2012 Pediatric Radiology Moore evaluates children with clinically suspected appendicitis as a primary tool. Methods 4 sequence protocol: Coronal and axial T2 Coronal SPAIR Axial T2 with fat saturation 208 children (age 3 17) with clinically suspected appendicitis No contrast No sedation Results May 2013 AJR 208 MRIs Age 3 17 years 2 incomplete studies without sedation Sensitivity of 97.6%, Specificity of 97% 40 true positive cases 5 false positive cases: looked inflamed intraoperatively but negative at pathology 1 false negative case 162 true negative cases 8

9 Methods Retrospective review of pediatric patients Dec April 2012 who had MRI appendicitis 67 patients total, 60 of which were performed within 24 hours Age 7 17 years Patient first had US and then clinician decided if patient needed an MRI based on inconclusive results (not identified or secondary signs) MRI reads compared to operative and pathology reports Results 10 true positives 2 false positives 48 true negatives Sensitivity and specificity of MRI for acute appendicitis in children with inconclusive US findings: 100% and 96% Positive findings in acute appendicitis by MRI Blind ending tubular structure Fluid filled lumen : hyperintense on T2, low on T1 Hyperintense periappendiceal tissues on T2 with enhancement reflects inflammation Appendiceal outer diameter >7mm Phlegmon or frank abscess Thickened appendiceal wall (can look like target sign as on US) with high signal on T2 images and enhancement Appendicolith is visualized as a signal void in the lumen (can be confused with gas in a normal caliber appendix) T2 9

10 Obstacles to getting an MRI through the ED How to overcome obstacles Scheduled patients? delay in care Scan time too long? delay in care Patients needing sedation?delay in care, problems with scheduling Availability after hours Cost Scheduled patients Scan time too long Patients needing sedation Availability and Cost Decrease exam time Decrease exam time Patient age and clinician assessment Decrease exam time Obstacle: sedation and time How can we decide which children get MRI? Patient selection is very important: Abdominal pain, RLQ pain, vomiting RLQ US yes/no, positive/negative? Patient age plays a key part in determining who can tolerate the MR without sedation. The ER physician in conjunction with the pediatric surgeon can help determine if the patient is capable of the MRI How can a pediatric patient tolerate an MRI without sedation? Age Patient comfort: Parent/caregiver in room MRI compatible goggles to watch movies 10

11 Pediatric Radiology 2001 Harned et al. studied MRI compatible audio/visual system: impact on pediatric sedation 955 patients Ages 3 10: decrease from 53 to 40% need for sedation > 10 years: decrease from 16 to 8% need for sedation Obstacle: time Decrease scan time! Which sequences are best, will help us get the child in and out quickly, and be the most useful in diagnosis. 17% decrease in room time for patients done without sedation Possible MRI protocol 1.5 Tesla magnet 8 channel array torso coil T2 weighted fluid sensitive sequences Dilated fluid filled appendix Periappendiceal inflammation Fluid collections Balanced SSFP (mixed T1 and T2 properties) Demonstrates bowel wall morphology Resists motion degradation T1 weighted images +/ T1 post contrast images Mucosal enhancement of inflamed appendix Appendiceal complications, ie. abscess Scan time ranges from minutes Which sequences are most useful? What is the utility of post contrast images? My colleagues and I did a study at Columbia University: To determine the value of gadolinium enhanced MR imaging in a pediatric population with acute appendicitis. To evaluate the sensitivity and specificity of different sequences with the goal of decreasing overall imaging time. What is the utility of post contrast images? Patients age 7 18, 64 patients Image Protocol: Axial and coronal T1 Axial and coronal T2 Axial and coronal balanced SSFP Axial and coronal post contrast T1 Sensitivities and specificities were obtained for each sequence independently and combined Results When all sequences were reviewed together, sensitivity of 94% and specificity of 100% Mean sensitivity and specificity for post contrast images was 94% and 100% Mean sensitivity and specificity for T2 images was 88% and 97% T1 post contrast images and T2 weighted images proved most helpful in the assessment of pediatric appendicitis 11

12 16-year-old female with abdominal pain and leukocytosis. 16 year old male with acute right lower quadrant pain and nausea. Contrast enhanced coronal images reveal a dilated appendix with wall enhancement. Phlegmonous enhancement is also seen surrounding the appendiceal tip. 9 year old male with acute abdominal pain. 12 year old male with acute right lower quadrant abdominal pain. Patient underwent an appendectomy with pathology confirming acute appendicitis. Proposed MR appendicitis protocol Current MR protocol Axial T2 Coronal T2 +/ Sagittal T2 Coronal bssfp Axial bssfp Axial post contrast Coronal post contrast Proposed MR protocol Axial T2 Coronal T2 Axial post contrast Coronal post contrast Total scan time = min So we save radiation but what about morbidities secondary to MR versus CT? Is there a difference in clinical end points in patients imaged by US/MRI versus US/CT? 2014 study in Pediatrics: Ultrasound/MRI versus CT for Diagnosing Appendicitis Aspelund et al. Columbia Total scan time = min 12

13 US/MRI versus CT Retrospective review of 662 patients <18 years old Divided patients into Group A and Group B Group A: Nov 2008 Oct 2010 CT with oral and IV (265 patients) Group B: Nov 2010 Oct 2102 US followed by MRI (397 patients) Age range of patients: CT: 2 18 years US: 1 18 years MRI: 5 18 years (not attempted under 5 years) Looked at clinical end points: length of stay, time to appendectomy, etc. Times (mean) group A vs group B Time to CT: 6.7 hours and 10.9 hours Time to MRI: 9.3 hours and 12.6 hours Time to antibiotics: 8.7 hours and 8.2 hours Time to appendectomy: 13.2 hours and 13.9 hours Length of stay: 52.2 hours and 43.4 hours Despite longer average time to imaging for group B, there was no difference in time from ED triage to antibiotics or appendectomy or length of stay. MRI is valuable in the work up of appendicitis High sensitivity and specificity ALARA principal Alternate diagnoses Most common alternate diagnoses Hormann s Imaging of Acute Appendicitis in Children: MRI 2011 Gastrointestinal IBD Meckel s diverticula Hernia Intussusception Mesenteric lymphadenitis Gynecological Ovarian torsion Ruptured cyst First menses Urological UPJ obstruction Pyelonephritis Calculus with obstruction Nonspecific Thoracic Basal pneumonia Musculoskeletal Osteitis ischiopubica Torsed right ovary 13

14 RLL pneumonia Ileus secondary to perforated duplication cyst There remains a role for CT Post operative complications Equivocal ultrasound in a child who would need sedation or anesthesia for MRI Time critical Abscess drainage Post operative drainage References Acknowledgements 1. Abo A, Shannon M, Taylor G, et al (2011) The Influence of Body Mass Index on the Accuracy of Ultrasound and Computed Tomography in Diagnosing Appendicitis in Children. Pediatric Emergency Care Brenner, D.J.; Hall, E.J. Computed Tomography an Increasing Source of Radiation Exposure. New England Journal of Medicine. 2007; 357: Brenner DJ, Elliston CD, Hall Eric J et al (2001) Estimated Risks of Radiation Induced Fatal Cancer from Pediatric CT. AJR 2001; 176: Cobben L, Groot I, Kingma L et al (2008) A simple MRI protocol in patients with clinically suspected appendicitis: results in 138 patients and effect on outcome of appendectomy. Eur Radiol 19: Hormann M, Paya K, Eibenberger K et al (1998) MR Imaging in Children with Nonperforated Acute Appendicitis: Value of Unenhanced MR Imaging in Sonographically Selected Cases. AJR 171: Hormann M, Puig S, Prokesch SR et al (2002) MR Imaging of the normal appendix in children. Eur Radiol 12: Moore M, Gustas C, Choudhary A et al (2011) MRI for clinically suspected pediatric appendicitis: an implemented program. Pediatr Radiol 8. Rao PM, Rhea JT, Novelline RA, et al. (1997) Helical CT Technique for the diagnosis of Appendicitis: prospective evaluation of afocused appendix CT examination. Radiology Volume 202: Issue 1, Rao PM, Rhea JT, Novelline RA, et al. (1997) Sensitivity and Specificity of Individual Signs of Appendicitis:Experience with 200 Helical Appendiceal Examinations. Journal of Computer Assisted Tomography, Sept/Oct 1997 Volume 21 Issue Dr. Carrie Ruzal Shapiro Dr. Susie Chen Dr. Lucila Rosines Dr. Rama Ayala Dr. Brian Coley 10. Pena PMG, Mandl KD, Kraus SJ et al (1999) Ultrasonography and Limited Computed Tomography in the Diagnosis and Management of Appendicitis in Children. JAMA 1999; 282 (11): Rosendahl K, Aukland SM, Fosse K (2004) Imaging Strategies in Children with suspected appendicitis. Eur Radiol 14:L138 L Samuel, Madan (2002) Pediatric Appendicitis Score. Journal of Pediatric Surgery 37: Singh A, Danrad R, Hahn P, et al (2007) MR Imaging of the Acute Abdomen and Pelvis: Acute Appendicitis and Beyond. Radiographics 27: Tkacz J, Anderson S, Soto J (2009) MR Imaging in Gastrointestinal emergencies. Radiographics 29: