MDCT of Acute Right Lower Quadrant Pain; Appendicitis & Conditions that Mimic Appendicitis

Transcription

1 Baltic Congress of Radiology, Riga 2010 MDCT of Acute Right Lower Quadrant Pain; Appendicitis & Conditions that Mimic Appendicitis Robert A. Novelline, MD Professor of Radiology, Harvard Medical School Director of Emergency Radiology, Massachusetts General Hospital

2 Differential Diagnosis: RLQ Pain Gastrointestinal Appendicitis Diverticulitis Epiploic Appendagitis Segmental Omental Infarction Ileocolitis Mesenteric Adenitis Cecal Carcinoma Crohn Disease Meckel Diverticulitis Cholecystitis Gynecological Hemorrhagic Ovarian Cyst Ruptured Ovarian Cyst Ectopic Pregnancy Adnexal Torsion Pelvic Inflammatory Disease with Tubo-Ovarian Abscess Degenerating Uterine Leiomyoma Urological Nephrolithiasis Pyelonephritis Hydronephrosis

3 Common Causes of Acute RLQ Pain in Emergency Department Patients Appendicitis Mimics of Appendicitis Causing Acute RLQ Pain: Right-sided Diverticulitis Meckel s Diverticulitis Crohn Disease Typhlitis (Neutropenic colitis) Mesenteric Adenitis Right-Sided Segmental Omental Infarction Right-Sided Hernia Cecal Volvulus Right-Sided Tubo-Ovarian Abscess

4 Appendicitis

5 Appendicitis Most common acute surgical condition of abdomen 7% population will have appendicitis in their lifetime Peak incidence: ages years 250,000 new cases/year in USA Approximately 10 to 30% frequency of perforation 7 to 33% are not apparent clinically. 20% of emergency appendectomies reveal normal appendix (prior to routine use of CT)

6 Etiology of Appendicitis Obstruction of appendiceal lumen Venous obstruction Ischemia Bacterial invasion Necrosis

7 Presenting Signs and Symptoms of Acute Appendicitis RLQ pain and/or tenderness 96% Duration of symptoms < 5 days 80% WBC > 10,000/mm3 66% Temperature > 37.5 C (99.5 F) 63% Nausea 62% Vomiting 32% Rebound tenderness 26% Anorexia 24% RLQ guarding 21%

8 Focused MDCT Protocol for Appendicitis Rectal Contrast; Limited MDCT Scan Rectal Contrast: 40cc of 60% contrast in 1000cc saline IV Contrast: cc of cc/sec Followed by 50cc saline MDCT Scan Protocol Scan after 150 sec delay Scan from L3 to acetabular roof (reduce radiation) Auto exposure reduction (ACTM) View slices at 2.5mm thickness Routine coronal and sagittal reformations If no appendicitis seen and no alternative diagnosis Extend scan to full abdomen

9 Colon Contrast Advantages Faster Normal appendix fills better Cecal apical changes seen better due to cecal distention Higher reported accuracy Greater interpreter confidence Avoids Delays waiting for oral contrast Nauseated patients do not need to drink large amounts of contrast General anesthesia problems after CT

10 Finding the Appendix at CT Find ileocecal valve as a landmark (40% of patients reflux into terminal ileum) Origin of appendix is 2-3 cm caudal to valve, and usually posteromedial Location: variable Follow appendix to its blind-ending tip Note the various positions above!!

11 Normal Appendix Lumen filling at CT Contrast, air, both Outer Diameter < 10mm Lumen not filling Outer Diameter < 6mm

12 Normal Appendix at CT Normal filled with contrast Appendicitis Normal filled with contrast Normal filled with air

13 Normal Appendix Filled with Contrast

14 CT Signs of Appendicitis Abnormal Appendix Periappendiceal Inflammation Cecal Apical Changes Diameter >6mm Fails to completely fill with contrast Appendoliths Wall thickening Wall enhancement with IV contrast Fat stranding Fluid Phlegmon Extraluminal air bubbles Abscess Adenopathy Focal apical thickening Arrowhead sign Cecal bar

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31 Interpretation of the Images: Appendicitis is Excluded! Normal Appendix: See normal appendix in about 94% of patients who do not have appendicitis with MDCT Fills with air and/or contrast (73%) No filling but diameter less than 6mm May see pencil-line, thin wall If appendix is not seen and there are no signs of inflammation in or about the cecum

32 Interpretation of the Images: Appendicitis is Diagnosed! Abnormal Appendix: Does not fill with air and/or contrast Is greater than 6mm in diameter Centered within fat stranding or consumed by phlegmon/abscess Cecal apical changes: focal cecal apical thickening, cecal bar, arrowhead sign Appendoliths May see thickened higher density wall

33 Appendoliths Are seen in up to 45% of cases using CT Must be seen in conjunction with other signs of appendicitis May or may not be calcified uniformly May contain air

34 Appendoliths may be seen on radiographs, Supine Upright

35 But, are much better shown by CT, and CT can show appendicitis!

36 Peri-Appendiceal Inflammation In soft tissues surrounding or adjacent to appendix see fat stranding, fluid, phlegmon, extraluminal air bubbles, abscess or adenopathy Adenopathy usually present with appendicitis located anterior to psoas just cephalad to origin of appendix; also see with mesenteric adenitis Phlegmon (inflamed soft tissue mass) may prevent visualization of abnormal appendix Value of IV contrast material With phlegmon diagnosis appendicitis based on: Appendoliths Cecal apical changes specific for appendicitis

37 Appendicitis With Phlegmon Value of IV Contrast Material No IV Contrast Material With IV Contrast Material

38 Appendoliths in Phlegmon 7 year old with Appendicitis

39 Cecal Apical Findings 1. Focal cecal apical thickening 2. Arrowhead sign 3. Cecal bar

40 Cecal Apical Findings 1. Focal cecal apical thickening Caused by spread of inflammation and edema into wall of cecum Complete filling of cecum with contrast is needed to visualize this sign The sign is frequent and pathognomonic for appendicitis Focal wall thickening from diverticulitis is centered at the diverticulum, not the cecal apex

41 1. Focal cecal apical thickening

42 Cecal Apical Findings 2. Arrowhead Sign Inflammatory thickening of cecal apex with contrast funneling into center of inflammation Visualization depends on CT slice coinciding with position of arrowhead Arrowhead points toward appendix Appendolith

43 Cecal Apical Findings 3. Cecal bar Inflamed soft tissues surrounding an obstructing proximal appendolith Thickened bar of soft tissue separates appendolith from lumen of cecum Bar Appendolith

44 Ruptured Appendicitis

45 Ruptured Appendicitis

46 Appendicitis in Pregnancy Imaging Options Ultrasound Limited CT scan in 3 rd trimester MR scan in 1 st and 2 nd trimester

47 Wall enhancement Fat Stranding Dilated appendix (>6mm)

48 Normal Appendix at MR Normal Appendix (MR) Caliber: < 7 mm Wall: < 2 mm Periappendical: No inflammation Medium intensity No fluid in the lumen Seen in % Cecum Placenta Appendix Psoas major Cecum Appendix T2 FSE

49 MR of Acute Appendicitis Abnormal Appendix (MR) Caliber: >/= 7 mm Wall: Hypo on T1 & Hyper on T2 Periappendiceal inflammation Ascites STIR

50 *Distal (Tip) Appendicitis Appendicitis usually results from luminal obstruction at the appendiceal orifice When lumen is obstructed distal to orifice the resulting condition is distal/tip appendicitis Lumen of proximal appendix may opacify and appear normal resulting in a false negative diagnosis of appendicitis This condition is readily recognized by CT *Rao PM, Rhea JT, Novelline RA. Distal appendicitis: CT appearance and diagnosis. Radiology. 204: , 1997.

51 Distal (Tip) Appendicitis

52 Tip Appendicitis

53 Thoracic Appendicitis Patient with known large diaphragmatic hernia Now presents with left lower chest pain, fever and elevated WBC Cecum

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55 Thoracic Appendicitis

56 Accuracy of CT for Appendicitis Sensitivity Specificity Accuracy (%) (%) (%) Balthazar IV and Oral Contrast, Radiology, 1994, Alternative diagnosis in 48% Lane No Contrast, AJR, 1997, Alternative diagnosis in 35% Rao Colon Contrast, AJR, 1997, Alternative diagnosis in 62% Normal appendix seen in 43, 71, and 94%

57 Right-Sided Diverticulitis

58 Right-Sided Diverticulitis Diverticulitis may produce RLQ pain when involving the cecum and right colon, or if sigmoid diverticulitis extends to the right Combination of RLQ pain, fever and leukocytosis can mimic appendicitis Look for a normal appendix at CT

59 Right-Sided Diverticulitis with Normal Appendix

60 Right-Sided Diverticulitis; Normal Appendix

61 Meckel s Diverticulitis

62 Meckel s Diverticulum 1-Small bowel loops 2-Meckel s diverticulum Congenital anomaly of small bowel; remnant of vitelline duct Occurs in 2% population Located antimesenteric border of small bowel, cm before terminal ileum Complications: Bowel obstruction (35%), Hemorrhage (32%) Diverticulitis (22%) Meckel s diverticulitis clinically mimics acute appendicitis

63 Meckel s Diverticulitis 70 year old man with RLQ pain and fever

64 Meckel s Diverticulitis 70 year old man with RLQ pain and fever Normal Appendix

65 Meckel s Diverticulum 15 year old girl with lower GI bleeding and crampy abdominal pain

66 Normal appendix Meckel s

67 Crohn Disease

68 Crohn (Chron s) Disease Inflammatory disease of the distal small bowel which may involve cecum and right colon CT shows wall thickening and enhancement CT may also show complications such as abscess, perforation, fistula or stricture May be associated with secondary appendicitis

69 Chron Disease in a 30 year old woman with acute RLQ pain and fever

70 Chron Disease in a 30 year old woman with acute RLQ pain and fever

71 Crohn Disease with Perforation

72 Crohn Disease with Perforation

73 Typhlitis

74 Typhlitis (Neutropenic Enterocolitis) In neutropenic (neutrophils< 1000/mL) patients undergoing treatment for malignancy, often acute leukemia, terminal lymphoma, aplastic anemia Fever, watery or bloody diarrhea and abdominal pain often localized to the right lower quadrant Edema and inflammation of the cecum and ascending colon Transmural necrosis, perforation and death may occur (45% mortality) CT shows cecal distension cecal wall thickening with fat stranding

75 Typhlitis: 59 yo Male with Aplastic Anemia, Neutropenia and New RLQ Pain Note thick walled ascending colon Vs normal wall of descending colon

76 Mesenteric Adenitis

77 Mesenteric Adenitis Primary Mesenteric Adenitis Adenitis without an acute inflammatory process May see mild thickening of the terminal ileum Self-limited process that affects lymph nodes in the RLQ Non-surgical condition, more common under 15 years Presentation may mimic appendicitis Etiology: infection with viral and other pathogens Secondary Mesenteric Adenitis Adenopathy with Crohn Disease, ileitis, appendicitis, diverticulitis, or neoplasms (lymphoma, carcinoma)

78 CT Findings in Mesenteric Adenitis Enlarged (>5 mm shortest dimension) and clustered (3 or more) mesenteric nodes Location in RLQ Anterior to psoas Small bowel mesentery Adenitis may be associated with small bowel wall thickening (>3 mm)

79 Primary Mesenteric Adenitis 35 year old with RLQ pain and leukocytosis Note the enlarged RLQ nodes and normal appendix!

80 Right-Sided Omental Infarction

81 Segmental Omental Infarction Rare clinical entity Etiology of infarction Necrosis caused by interruption of blood supply to omentum from torsion or venous thrombosis More common on right side Primary (idiopathic) or Secondary torsion (adhesions, neoplasm, trauma, surgery, hernia) Primary precipitated by coughing, straining, overeating Clinical presentation Sudden, severe abdominal pain, RLQ or peri-umbilical tenderness, may have fever Differential Diagnosis Appendicitis, diverticulitis, cholecystitis Metastases, liposarcoma, secondarily inflamed fat

82 CT Findings in Segmental Omental Infarction CT shows an abdominal mass (ovoid, cake-like) of fat stranding or fat with dense streaks representing folds within the mass Superficial location Between abdominal wall muscle and bowel/abdominal organs Right-sided > left-sided Complications: Necrosis and abscess

83 Right-Sided Omental Infarction RLQ pain thought to have appendicitis

84 Right-Sided Hernia

85 Right-Sided Incarcerated Spigelian Hernia 79 Year old male with RLQ pain which progressed to diffuse crampy abdominal pain and obstipation

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87 Cecal Volvulus

88 Cecal Volvulus in 45 year old woman with sudden onset RLQ pain

89 Note Value of Coronal Reformations!

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99 Cecal Volvulus A form of closed loop obstruction Occurs in a small percentage of the population with developmental failure of fixation of the proximal colon At surgery cecal volvulus was present with congenital absence of attachment of cecum to the right abdominal wall and marked edema of the cecum Patient underwent right colectomy

100 Right-Sided Tubo-Ovarian Abscess (TOA)

101 Tubo-Ovarian Abscess (TOA) Advanced form pelvic inflammatory disease (PID) Often caused by Chlamydia trachomatis and Neisseria gonorrhoeae Infection of ovary and fallopian tube with hydrosalpinx and collection of pus Present with pain, fever, vaginal discharge Usually diagnosed by ultrasound CT may show a complex cystic mass representing dilated tubes and the TOA

102 Tubo-Ovarian Abscess

103 Summary In the emergency department consider the following causes of acute RLQ pain: Appendicitis Mimics of Appendicitis: Right-sided Diverticulitis Meckel s Diverticulitis Crohn Disease Typhlitis (Neutropenic Colitis) Mesenteric Adenitis Right-Sided Segmental Omental Infarction Right-Sided Hernia Cecal Volvulus Right-Sided Tubo-Ovarian Abscess

104 Thank You! Robert A. Novelline, MD Professor of Radiology, Harvard Medical School Director of Emergency Radiology, Massachusetts General Hospital