11 improved outcomes in colon and rectal surgery called to do so. The US beam will be completely reflected by bone and sufficiently scattered by air to thwart imaging distal to these substances. When the transmitted sound wave reflects off a moving target, the returning echo will have a slightly different frequency (the Doppler Effect). Doppler US capitalizes on this principle and allows the determination of direction and veloc- ity of a mobile target.(250) The most frequent application for Doppler US is the detection and quantification of blood flow. Specifically, Doppler US is extremely helpful in evaluating the upper and lower extremities for deep venous thrombosis. US has many advantages. It is an inexpensive, widely available modality that provides real time, multiplanar images with no radiation exposure to the patient. The US equipment is mobile, allowing critically ill patients to be imaged within the ICU. The structures that can be studied by US include arteries, veins, liver, spleen, gallbladder, bile ducts, pancreas, kidneys, bladder, uterus, and ovaries. Transabdominal US is typically limited in its evalu- ation of the gastrointestinal tract. Intraluminal bowel gas will obscure the surrounding anatomy. Therefore, patients should be NPO for 4 to 8 hours before being imaged to reduce the volume of intraluminal gas.(251) Nonetheless, US can detect abnormal loops of bowel. Wall thickening, hyperemia, fecoliths, bowel dis- tention, wall edema, and noncompressibility all can be detected by ultrasound and suggest intestinal pathology. US can be helpful in diagnosing a wide variety of disease processes including appendi- citis (Figure 11.49), intussusception, inflammatory bowel disease, colitis (from numerous causes), and neoplasm (Figure 11.50). Due to the superior sensitivity and specificity of other imaging modalities, US evaluation of the bowel is typically reserved for situations where limitation of radiation exposure is desired (i.e., pediatric and pregnant patients). Figure 11.50 Colon Cancer Liver Metastasis. US of the liver demonstrates an isoechoic mass with a hypoechoic peripheral halo. This “target” appearance can be seen in a variety of disease processes but is a common finding in metastatic colon cancer and hepatocellular carcinoma. Figure 11.51 Normal Layers of Colon on Intrarectal ultrasound (Graphic representation of 5 layers). Figure 11.52 Normal Endoluminal Ultrasound. Figure 11.53 Ultrasound of uT3 rectal mass. 11 limitations of colorectal imaging studies Intraoperative ultrasound (IUS) can provide important infor- mation to the surgeon and is commonly used to evaluate the liver for metastatic disease and guide the subsequent metastasectomy. IUS is particularly useful in delineating the relationship between hepatic tumors and adjacent vasculature.(252) Studies have shown that IUS provides vital information to the surgeon during the procedure that will affect surgical decision making in up to 38% hepatic metastasectomy.(251) Endoluminal Ultrasound Endoluminal ultrasound’s (EUS) impact on the workup for col- orectal cancer continues to expand. Transrectal US appears to be the most accurate imaging modality in determining the extent of local invasion of rectal cancer.(253) EUS can delineate the components of the intestinal wall. Images typically consist of five rings of different echogenicity (3 hyperechoic and 2 hypoechoic) that allow the localization of the mucosa, muscularis mucosa, submusoca, muscularis propria, and serosa (254)) (Figure 11.51). Colorectal tumors will appear as a hypoechoic mass that distorts the normal bowel architecture (Figure 11.52 and 11.53). EUS can accurately identify the specific layers of the bowel wall invasion, thereby elucidating the tumor stage.(255) Recent studies have shown that transrectal US has difficulty differentiating between tumor and peritumoral inflammation, thereby producing a ten- dency to over stage a recently diagnosed cancer. EUS is often used in conjunction with traditional endoscopy to allow direct visual- ization of the mucosa, assess the depth of wall involvement, facili- tate biopsy, and evaluate for pericolonic lymphadenopathy. While EUS has the ability to detect local lymph node involvement, cross sectional imaging (CT, MRI, or PET) is still needed to evaluate for regional and distant metastatic disease.(255) Nononcologic applications of EUS include the evaluation of the colon, rectum, and anus for strictures, fistulas, and abscesses. Transanal US is often used in the evaluation of incontinence as it can detect defects within the internal anal sphincter, external anal sphincter, puborectalis sling, and pelvic musculature.(254) magnetic resonance imaging (mri) In magnetic resonance imaging, strong magnetic fields and tar- geted radiofrequency pulses are harnessed to map the location of protons within the body. Depending on the specific imaging parameters utilized, protons within fat (T1 MRI sequences), or water (T2 MRI sequences) can be selectively displayed. Ionizing radiation and iodinated contrast agents are not used. MRI images are degraded by motion and the combination of bowel peristalsis and diaphragmatic movement has traditionally limited the appli- cation of MRI in the evaluation of gastrointestinal pathology. (254) Ferromagnetic metals cannot be taken into the magnetic field and therefore most surgical implanted devices have been transitioned to MRI compatible materials. Care must still be taken with certain implanted devices as the strong magnetic field may cause malfunction. Confirmation of MRI compatibility with the manufacturer is required for implanted devices such as car- diac pacemakers, cochlear implants, spinal cord stimulators, and basal ganglion stimulation devices. Nephrogenic systemic fibrosis (NSF) is a disorder seen exclusively in patients with chronic renal insufficiency that presents with diffuse systemic sclerosis with particularly severe cutaneous fibrosis. In 1997, NSF was linked to gadolinium exposure in patients with renal insufficiency. The FDA has recently placed a black box warning on gadolinium containing MRI contrast agents.(256) Technological advancement with quicker image acquisition has reduced motion blurring and has allowed the diagnostic assessment of the sigmoid colon and rectum (anatomically fixed structures). (257) While MRI can be useful in the diagnosis of inflammation of the GI tract (for example, appendicitis, Crohn’s disease, and ulcer- ative colitis) (Figure 11.54), the largest advances have been made in evaluation of colorectal cancer.(254) The effectiveness of MRI is similar to CT for the initial staging of colorectal tumors.(258) MRI is very accurate evaluating the pelvis for local rectal tumor Figure 11.54 A and 11.54B Terminal Ileitis in Crohn’s Disease. Axial (A) and coronal (B) T1-fat saturated MRI images demonstrate mucosal enhancement within the terminal ileum (arrow) with no enhancement in the adjacent normal ileum (arrow head). The mucosal enhancement indicates active terminal ileitis. (a) (b) 1 improved outcomes in colon and rectal surgery extension (Figure 11.55), and has an advantage over CT in the evaluation of tumoral invasion of the levator ani, mesorectal fascia, internal and external sphincter muscles.(258–259) Endorectal MRI is a promising new technique that can help evaluate the depth of local tumor invasion. Endorectal ultrasound has been shown to be equally sensitive and specific as our currently available endorectal MRI and can be performed in a fraction of the time.(258, 260) MRI is also a valuable tool in detecting distant metastatic disease. Metastatic foci within the brain, skeleton, and liver are readily detected with MRI. Local tumor recurrence can be dif- ferentiated from mature fibrosis if the surgical resection was at least 1 year prior. Unfortunately, immature fibrosis (<1 year old) cannot be successfully distinguished from recurrent tumor with MRI.(258, 259) nucLear medicine imaging Positron Emission Tomography Positron Emission Tomography (PET) has been approved by Medicare for the diagnosis, staging, and restaging of colorectal cancer since 2001.(261) Unlike other imaging modalities that rely on architectural distortion, PET scans detect neoplasm based on physiologic differences between normal tissue and cancer cells. Malignant cells have a higher baseline metabolic state, increased mitotic activity, and consume more glucose. PET scans utilize the glucose analog F-18 fluorodeoxyglucose (F-18 FDG). F-18 FDG is transported into the cell through transmembrane glucose transporters but, unlike glucose, it does not undergo further metabolism.(261, 262) This causes an accumulation of F-18 FDG within the tumor cell. Fluorine-18 emits positrons that subsequently undergo annihilation when contacted by electrons. This annihilation produces gamma photons that are summated by specialized detectors and allow image generation. The photon count and inferred amount of glucose uptake is reported in standard uptake values (SUVs). The SUV takes into consideration the dose of F-18 FDG injected and body surface Figure 11.55 Perirectal Mass. Fluid sensitive (STIR) T2 MRI of the pelvis shows a hyperintense mass adjacent to the rectum, worrisome for rectal carcinoma. However, after resection, this mass was found to be a high grade liposarcoma. (a) (b) Figure 11.56 A–11.56C Comparison between CT and PET. Figure 11.56A demonstrates multiple discrete areas of hypermetabolism within the liver on PET scan, representing metastatic colon adenocarcinoma. Figure 11.56B shows a noncontrast CT scan of the same patient. The multiple metastatic foci are nearly impossible to detect without contrast. Figure 11.56C. Iodinated contrast helps to delineate between normal hepatic tissue and hypodense metastatic disease. (c) 11 limitations of colorectal imaging studies area.(261) In general, a SUV value above 2.5 is suspicious for malignancy but may also be secondary to an inflammatory or infectious process.(262) Care must be taken when relying on SUVs as they are only semi-quantitative and many variables affect the reported numeric value. One particularly strong variable is the serum glucose. A high serum glucose level will reduce tumor uptake of F-18 FDG and lower SUV values. Patients typically fast overnight and avoid carbohydrates before the procedure.(262) Blood glucose levels are checked before the examination with a level below 200 mg/dl desired. PET imaging of the colon is very sensitive (>90%) but lacks specificity (40–60%) due to physiologic bowel glucose uptake and hypermetabolic benign lesions, including colitis and benign pol- yps.(262) The main advantage of PET is its superiority over CT in the detection of metastatic colorectal cancer. PET will detect increased glucose metabolism in regional lymph nodes or dis- tant metastatic sites (Figure 11.56) that do demonstrate enough architectural distortion to be detected as abnormal by CT exami- nation. PET has also been shown to be superior to CT in the eval- uation of colorectal cancer recurrence (Figure 11.57) (263). PET can help monitor response to chemotherapy and radiation treat- ment but does not have the ability to detect microscopic residual disease (262). One of the main limitations of PET is low spatial resolution. This problem has largely been overcome by a new technique that allows the concurrent acquisition of PET and CT images dur- ing a single examination. PET/CT augments the localization of malignancy in contiguous or overlapping structures.(262) Differentiation of tumor from infection is problematic when the standard uptake value is only minimally elevated as regional lym- phocytes will metabolize an abundance of F-18 FDG. Likewise, colonic adenomas/polyps can demonstrate hypermetabolism and be misinterpreted as a tumor. Tumors that have a low cell density, small size, or low metabolic activity (including carcinoid and mucinous adenocarcinoma) have a higher likelihood of a false-negative result.(261, 262) Gastrointestinal Scintigraphy Nuclear medicine scintigraphy is a useful tool for the colorectal surgeon. A biologically significant substance (RBC, leukocyte) is labeled with a radioactive isotope that will subsequently emit gamma radiation. These gamma photons are detected by scin- tillation cameras and diagnostic images are generated. Nuclear medicine scintigraphy is especially helpful in answering a specific question. The evaluation for intraabdominal abscess, Meckel’s diverticulum, carcinoid tumor, biliary abnormality, pernicious anemia, and colonic transit time can be performed with radio- isotope labeled leukocytes, technetium, octreotide, iminodia- cetic acid, vitamin B12, and diethylene triamine pentaacetic acid (DTPA), respectively.(264) With the expanding use of fused PET-CT imaging, traditional nuclear medicine scintigraphy has a limited role in the manage- ment of colorectal neoplasia. In tumors that are known to have high false negative PET rates (i.e., mucinous adenocarcinoma), radioisotope labeled monoclonal antibodies may help in evaluat- ing for occult metastatic disease or recurrence.(264, 265) While multiple monoclonal antibodies have been approved by the FDA, none are currently in widespread clinical use.(266) Tc-99m red blood cell scintigraphy is a frequently utilized examination for the evaluation of lower gastrointestinal bleed- ing. The patient’s RBCs are labeled with the radioisotope tech- netium-99m (employing either an in-vivo or in-vitro method) in an attempt to identify red blood cells within the lumen of the GI tract, thereby localizing the source of bleeding. Three criteria are needed to confirm a gastrointestinal bleed. The radiotracer uptake pattern should conform to bowel anatomy, increase in intensity over time, and propagate in an antegrade or retrograde fashion (Figure 11.58). Multiple intraabominal abnormalities, including hepatic hemangiomas, accessory splenic tissue, or colonic angiodysplasia, can simulate a GI bleed but these abnor- malities will not change in location over time. A false negative Tc-99m RBC scintigram can be secondary to a slow intesti- nal bleeding rate or an intermittent bleed.(266) The reported Figure 11.57 PET-CT. PET-CT images show a focal area of hypermetabolic activity in the presacral space, adjacent to the patient’s low anterior resection site for rectal cancer, representing an area of recurrence. Note that this lesion may have been overlooked on the noncontrast CT. 1 improved outcomes in colon and rectal surgery Figure 11.58 A and 11.58B. Lower Gastrointestinal Bleeding. Figure 11.58A shows a single image of a Tc-99m red blood cell scintigram with a GI bleed originating in the transverse colon, near the hepatic flexure. Figure 11.58B is taken 5 minutes later and shows the radiotracer uptake pattern conforming to bowel and moving in an antegrade fashion towards the splenic flexure. (a) (b) sensitivity and specificity of Tc-99m RBC imaging has been reported as high as 93% and 95%, respectively.(264, 266) Tc-99m RBC scintigraphy can detect GI bleeding rates as low as 0.2 cc/ minute (compared to 1.0 cc/minute for traditional angiography), and is a sensitive tool that can help isolate the vascular territory of a bleed and direct percutaneous or surgical intervention.(266, 267) In an unstable patient, a Tc-99m sulfur colloid can be used to detect GI bleeding. Sulfur colloid scintigraphy requires less time for patient preparation and image acquisition but has a lower sensitivity for detecting gastrointestinal bleeding. interVentionaL radioLogy Gastrointestinal (GI) Bleeding The angiographic diagnosis of GI bleeding is based upon visual- ization of extravasation of contrast into the bowel lumen, and a high rate of bleeding (1 cc/min) is required to visualize extravasa- tion.(268) Angiograms are positive in only about 50% of patients, and a positive Tc-99m RBC scintigraphy scan within the first 5–9 minutes, makes angiography more likely to identify extravasa- tion.(269) The two techniques used for lower GI arterial bleeding are vasopressin infusion and embolization. Vasopressin (pitressin) infused into the proximal SMA or IMA causes both smooth muscle constriction and water reten- tion. Vasopressin can control lower GI bleeding in up to 90% of cases, and half of the patients will never bleed again. Vasopressin requires monitoring in an ICU. Rare complications include car- diac or digital ischemia from vasoconstriction, or hyponatremia from water retention.(268–270) Embolization controls GI bleeding by decreasing the arterial pressure and flow to the point that hemostasis can occur, with- out creating symptomatic ischemia. Large particles, Gelfoam, or microcoils can be used. Embolization is successful in over 90% of cases, with few instances of bowel ischemia. Rebleeding is reported to occur in 20% of patients. Patients should be moni- tored for bowel ischemia. Delayed ischemic colonic strictures have been reported.(268–270) Percutaneous Abscess Drainage (PAD) Percutaneous abscess drainage (PAD) has played a major role in decreasing the morbidity and mortality associated with surgical Figure 11.59 Percutaneous Abscess Drainage. Axial CT image demonstrates needle placement into the large fluid/air filled abscess. 1 limitations of colorectal imaging studies exploration. CT is the most appropriate modality in image guided PAD (Figure 11.59).(271) PAD of an intraabdominal abscess is effective with a single treatment in 70% of patients and increased to 82% if a second drainage is performed.(272) The overall findings from a large series of 2311 PADs report a success rate of 80–85%.(273) Complication rates of PAD are between none and 10%. Vascular laceration may occur and, if the vessel is small, the bleeding will usually stop spontaneously.(274) Percutaneous abscess drainage may be complicated by bowel perforation from the needle or catheter transversing the bowel. If the patient devel- ops signs of peritonitis after catheter penetration of bowel, then surgical intervention may be required.(275) Image-guided Percutaneous Biopsy The majority of image-guided biopsies can be performed on an outpatient basis. All interventional procedures can result in bleed- ing, but this complication can be reduced by correction of any coagulopathy before the procedure.(276) US offers the advantage of real-time needle visualization, low cost, portable, and no ion- izing radiation (Figure 11.60). US guidance can be problematic in obese patients because the echogenic needle can be hard to visualize in echogenic fat. Lesions located deep to bone or bowel cannot be biopsied with US owing to lack of visualization of the lesion. CT can be used to guide biopsy needles to virtually any area of the body. CT provides excellent visualization of lesions and allows accurate identification of organs between the skin and the lesion.(277) Disadvantages of CT include increased cost, ion- izing radiation, and longer procedure times. Complications of abdominal, liver, or lung biopsy include bleeding, introducing infection, pneumothorax, and hemoptysis. Postprocedure pneu- mothorax may occasionally require chest tube placement and observation in the hospital.(276, 277) Radiofrequency ablation (RFA) and Chemoembolization of Hepatic Metastasis Radiofrequency ablations (RFA) of liver metastasis are per- formed similar to image-guided needle biopsy, with the RF probe taking the place of the needle. The RF probe is placed in the hepatic tumor and vibrates at a high frequency, conduct- ing heat into and ablating the tumor.(278). Studies show that the overall 5-year survival rate for colorectal liver metastasis treated by RF ablation is similar to surgical series (25–40%). (279) There are no absolute contraindications, and relative con- traindications include low platelets and coagulopathy. RFA of hepatic tumors is associated with very low complication rates, generally below 2%. Complications include pain, pleural effu- sion, bleeding, and abscess formation.(278) The treatment of certain tumors (metastatic hepatic lesions) with intravascular delivery of chemotherapeutic agents can be palliative and prolong life, but is not considered curative.(280) A wide variety of chemotherapeutic regimens are used. These chemotherapeutic medications are usually mixed with an embo- lic agent that slows flow and allows the drugs to remain in the organ. Metastatic disease to the liver can also be embolized by Yttrium-loaded microspheres that emit beta-radiation. Fulminant hepatic failure or liver abscess formation occurs in <1% of patients. Gallbladder infarction due to chemoembolization is rare. (280–282) references 1. Bluth EI, Locascio LF Jr, Head SC, Smetherman D. Diagnostic imaging. In Beck DE, ed. Handbook of colorectal surgery. St. Louis: Quality Medical Publishing, 1997: 39–62. 2. Brant WE, Helms CA. Fundamentals of Diagnostic Radiology, 3rd ed, Vol III. Lippincott Williams & Wilkins, 2006: 737. 3. Maglinte DD, Kelvin FM, Sandrasegaran K et al. Radiology of small bowel obstruction: contemporary approach and controversies. Abdom Imaging 2005; 30: 160–78. 4. Brant WE, Helms CA. Fundamentals of Diagnostic Radiology, 3rd ed, Vol III. Lippincott Williams & Wilkins, 2006: 743. 5. Mutch MG, Birnbaum EH, Menias CO. ASCRS Textbook of Colon and Rectal Surgery, Chapter 6. New York: Springer- Verlag, 2006: 69–70. 6. Brant WE, Helms CA. Fundamentals of Diagnostic Radiology, 3rd ed, Vol III. Lippincott Williams & Wilkins, 2006: 745. 7. Levine MS. Plain film diagnosis of the acute abdomen. Emerg Med Clin North Am 1985; 3: 541–62. 8. McCook TA, Ravin CE, Rice RP. Abdominal radiography in the emergency department: a prospective analysis. Ann Emerg Med 1982; 11: 7–8. 9. Ahn SH, Mayo-Smith WW, Murphy BL, Reinert SE, Cronan JJ. Acute nontraumatic abdominal pain in adult patients: abdominal radiography compared with CT evaluation. Radiology 2002; 225: 159–64. 10. MacKersie AB, Lane MJ, Gerhardt RT et al. Nontraumatic Acute Abdominal Pain: Unenhanced Helical CT Compared with Three-View Acute Abdominal Series. Radiology 2005; 237: 114–22. 11. Birnbaum BA, Jeffrey RB Jr. CT and sonographic evaluation of acute right lower quadrant pain. AJR Am J Roentgenol 1998; 170: 361–71. Figure 11.60 US Guided Biopsy of Colon Cancer Liver Metastasis. US image demonstrates needle placement into hepatic tumor of uncertain etiology. This was proven to be metastatic colon adenocarcinoma by pathology. 1 improved outcomes in colon and rectal surgery 12. Malone AJ. Unenhanced CT in the evaluation of the acute abdomen: the community hospital experience. Semin Ultrasound CT MR 1999; 20: 68–76. 13. Rao PM, Rhea JT, Rao JA, Conn AKT. Plain abdominal radiography in clinically suspected appendicitis: diagnostic yield, resource use, and comparison with CT. Am J Emerg Med 1999; 17: 325–8. 14. Eisenberg RL, Heineken P, Hedgcock MW, Federle M, Goldberg HI. Evaluation of plain abdominal radiographs in the diagno- sis of abdominal pain. Ann Surg 1983; 197: 464–9. 15. Bohner H, Yang Q, Franke C, Verreet PR, Ohmann C. Simple data from history and physical examination help to exclude bowel obstruction and to avoid radiographic stud- ies in patients with acute abdominal pain. Eur J Surg 1998; 164: 777–84. 16. Patel NH, Lauber PR. The meaning of a nonspecific abdom- inal gas pattern. Acad Radiol 1995; 2: 667–9. 17. Siewert B, Raptopoulos V, Mueller MF, Rosen MP, Steer M. Impact of CT on diagnosis and management of acute abdo- men in patients initially treated without surgery. AJR Am J Roentgenol 1997; 168: 173–8. 18. Rosen MP, Sands DZ, Longmaid HE III et al. Impact of abdominal CT on the management of patients presenting to the emergency department with acute abdominal pain. AJR Am J Roentgenol 2000; 174: 1391–6. 19. Rao PM, Rhea JT, Novelline RA et al. Helical CT technique for the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination. Radiology 1997; 202: 139–44. 20. Smith RC, Rosenfield AT, Choe KA et al. Acute flank pain: comparison of non-contrast-enhanced CT and intravenous urography. Radiology 1995; 194: 789–94. 21. Megibow AJ, Balthazar EJ, Cho KC et al. Bowel obstruction: evaluation with CT. Radiology 1991; 180: 313–8. 22. Del Campo L, Arribas I, Valguena M, Mate J, Moreno-Otero R. Spiral CT findings in active and remission phases in patients with Crohn disease. J Comput Assist Tomogr 2001; 25: 792–7. 23. Jacobs JE, Birnbaum BA, Macari M et al. Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material. Radiology 2001; 220: 683–690. 24. Kim JK, Ha HK, Byun JY et al. CT differentiation of mesen- teric ischemia due to vasculitis and thromboembolic disease. J Comput Assist Tomogr 2001; 25: 604–11. 25. Kamel IR, Goldberg SN, Keogan MT, Rosen MP, Raptopoulos V. Right lower quadrant pain and suspected appendici- tis: nonfocused appendiceal CT—review of 100 cases. Radiology 2000; 217: 159–63. 26. Abramson S, Walders N, Applegate KE, Gilkeson RC, Robbin MR. Impact in the emergency department of unen- hanced CT on diagnostic confidence and therapeutic effi- cacy in patients with suspected renal colic: a prospective survey. 2000 ARRS President’s Award. American Roentgen Ray Society. AJR Am J Roentgenol 2000; 175: 1689–95. 27. Katz DS, Scheer M, Lumerman JH et al. Alternative or additional diagnoses on unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations. Urology 2000; 56: 53–7. 28. Dondelinger RF, Trotteur G, Ghaye B et al. Traumatic inju- ries radiological hemostatic intervention at admission. Eur Radiol 2002; 12: 979–93. 29. Petridis A, Pilavaki M, Vafiadis E et al. CT of hemody- namically unstable abdominal trauma. Eur Radiol 1999; 9: 250–5. 30. Poletti PA, Wintermark M, Schnyder P et al. Traumatic injuries: role of imaging in the management of the polytrauma victim (conservative expectation). Eur Radiol 2002; 12: 969–78. 31. Wolfman NT, Bechtold RE, Scharling ES et al. Blunt upper abdominal trauma: evaluation by CT. AJR Am J Roentgenol 1992; 158: 493–501. 32. Novelline RA, Rhea JT, Rao PM et al. Helical CT in emer- gency radiology. Radiology 1999; 213: 321–39. 33. Novelline RA, Rhea JT, Bell T. Helical CT of abdominal trauma. Radiol Clin North Am 1999; 37: 591–612. 34. Shreve WS, Knotts FB, Siders RW et al. Retrospective analysis of the adequacy of oral contrast material for com- puted tomography scans in trauma patients. Am J Surg 1999; 178: 14–7. 35. Stafford RE, McGonigal MD, Weiglt JA et al. Oral contrast solution and computed tomography for blunt abdominal trauma: a randomized study. Arch Surg 1999; 134: 622–6. 36. Federle MP. Computed tomography of blunt abdominal trauma. Radiol Clin North Am 1983; 21: 461–75. 37. Howell HS, Bartizal JF, Freeark RJ. Blunt trauma involving the colon and rectum. J Trauma 1976; 16: 624–32. 38. Johnson D, Hamer DB. Perforation of the transverse colon as a result of minor blunt abdominal trauma. Injury 1997; 28: 421–3. 39. Mirvis SE, Gens DR, Shanmuganathan K. Rupture of the bowel after blunt abdominal trauma: diagnosis with CT. AJR Am J Roentgenol 1992; 159: 1217–21. 40. Nghiem HV, Jeffrey RB, Mindelzun RE. CT of blunt trauma to the bowel and mesentery. AJR Am J Roentgenol 1993; 160: 53–8. 41. Orwig D, Federle MP. Localized clotted blood as evidence of visceral trauma on CT: the sentinel clot sign. AJR Am J Roentgenol 1989; 153: 747–9. 42. Rizzo MJ, Federle MP, Griffiths BG. Bowel and mesenteric injury following bluntabdominal trauma: evaluation with CT. Radiology 1989; 173: 143–8. 43. Berland LL. CT of blunt abdominal trauma. In: Fishman EK, Frederle MP, eds. Body CT categorical course syllabus. New Orleans, LA: Amercian Roentgen Ray Society, 1994: 207–14. 44. Breen DJ, Janzen DL, Zwirewich CV et al. Blunt bowel and mesenteric injury: diagnostic performance of CT signs. J Comput Assist Tomogr 1997; 21: 706–12. 45. Donohue JH, Federie MP, Griffiths BG et al. Computed tomography in the diagnosis of blunt intestinal and mesen- teric injuries. J Trauma 1987; 27: 11–7. 46. Levine CD, Gonzales RN, Wachsberg RH et al. CT findings of bowel and mesenteric injury. J Comput Assist Tomogr 1997; 21: 974–9. 1 limitations of colorectal imaging studies 47. Fakhry SM, Watts DD, Luchette FA et al. Current diagnos- tic approaches lack sensitivity in the diagnosis of perforated blunt small bowel injury: analysis from 275,557 trauma admissions from the east multi-institutional HVI trial. J Trauma 2003; 54: 295–306. 48. Dowe MF, Shanmuganathan K, Mirvis SE et al. CT find- ings of mesenteric injury after blunt trauma: implications for surgical intervention. AJR Am J Roentgenol 1997; 168: 425–8. 49. Macari M, Balthazar EJ. CT of bowel wall thickening: signif- icance and pitfalls of interpretation. AJR Am J Roentgenol 2001; 176: 1105–16. 50. Pereira JM, Sirlin CB, Pinto PS et al. Disproportionate fat stranding: a helpful CT sign in patients with acute abdomi- nal pain. RadioGraphics 2004; 24: 703–15. 51. Gore RM, Balthazar EJ, Ghahremani GG, Miller FH. CT features of ulcerative colitis and Crohn’s disease. AJR Am J Roentgenol 1996; 167: 3–15. 52. Gore RM. CT of inflammatory bowel disease. Radiol Clin North Am 1989; 27: 717–30. 53. Meyers MA, McGuire PV. Spiral CT demonstration of hypervascularity in Crohn Disease: “vascular jejunization of the ileum” or the “comb sign.” Abdom Imaging 1995; 20: 327–32. 54. Gore RM, Cohen MI, Vogelzang RL et al. Value of computed tomography in the detection of complications of Crohn’s disease. Dig Dis Sci 1985; 30: 701–9. 55. Kerber GW, Greenberg M, Rubin JM. Computed tomog- raphy evaluation of local and intestinal complications in Crohn’s disease. Gastrointest Radiol 1984; 9: 143–8. 56. Keighley MRB, Eastwood D, Ambrose NS et al. Incidence and microbiology of abdominal and pelvic abscess in Crohn’s disease. Gastroenterology 1982; 83: 1271–5. 57. Fukuya T, Hawes DR, Lu CC et al. CT of abdominal abscess with fistulous communication to the gastrointestinal tract. J Comput Assist Tomogr 1991; 15: 445–9. 58. Horton KM, Corl FM, Fishman EK. CT evaluation of the colon: Inflammatory disease. Radiographics 2000; 20: 399–418. 59. Birnbaum BA, Jeffrey RB. CT and sonographic evaluation of acute right lower quadrant abdominal pain. AJR Am J Roentgenol 1998; 170: 361–71. 60. Yu J, Fulcher AS, Turner MA, Halvorsen RA. Helical CT eval- uation of acute right lower quadrant pain. II. Uncommon mimics of appendicitis. AJR Am J Roentgenol 2005; 184: 1143–9. 61. Macari M, Balthazar EJ. CT of bowel wall thickening: signif- icance and pitfalls of interpretation. AJR Am J Roentgenol 2001; 176: 1105–16. 62. Rao PM, Rhea JT, Novelline RA. CT diagnosis of mesenteric adenitis. Radiology 1997; 202: 145–9. 63. Levy AD, Hobbs CM. Meckel diverticulum: radiologic fea- tures with pathologic correlation. RadioGraphics 2004; 24: 565–87. 64. Barbary C, Tissier S, Floquet M, Regent D. Imaging of complications of Meckel diverticulum. J Radiol 2004; 85: 273–9. 65. Bennett GL, Slywotzky CM, Giovanniello G. Gynecologic causes of acute pelvic pain: spectrum of CT findings. RadioGraphics 2002; 22: 785–801. 66. Sam JW, Jacobs JE, Birnbaum BA. Spectrum of CT findings in acute pyogenic pelvic inflammatory disease. RadioGraphics 2002; 22: 1327–34. 67. Jang HJ, Lim HK, Lee SJ et al. Acute diverticulitis of the cecum and ascending colon: the value of thin-section heli- cal CT findings in excluding colonic carcinoma. AJR Am J Roentgenol 2000; 174: 1397–402. 68. Balthazar EJ. Diverticular disease. In: Gore RM, Levine MS, Laufer I, eds. Textbook of GI radiology. Philadelphia, Pa: Saunders, 1994; 1072–95. 69. Balthazar EJ, Megibow A, Schinella RA, Gordon R. Limitations in the CT diagnosis of acute diverticulitis: com- parison of CT, contrast enema, and pathologic findings in 16 patients. AJR Am J Roentgenol 1990; 154: 281–5. 70. Padidar AM, Jeffrey RB Jr, Mindelzun RE, Dolph JF. Differentiating sigmoid diverticulitis from carcinoma on CT scans: mesenteric inflammation suggests diverticulitis. AJR Am J Roentgenol 1994; 163: 81–3. 71. Chintapalli KN, Esola CC, Chopra S, Ghiatas AA, Dodd GD. Pericolic mesenteric lymph nodes: an aid to distinguishing diverticulitis from cancer of the colon. AJR Am J Roentgenol 1997; 169: 1253–5. 72. Chintapalli KN, Chopra S, Ghiatas AA et al. Diverticulitis versus colon cancer: differentiation with helical CT find- ings. Radiology 1999; 210: 429–35. 73. Kircher MF, Rhea JT, Kihiczak D, Novelline RA. Frequency, sensitivity, and specificity of individual signs of diverticuli- tis on thin section helical CT with colonic contrast material: experience with 312 cases. AJR Am J Roentgenol 2002; 178: 1313–8. 74. Horton KM, Abrams, RA, Fishman, EK. Spiral CT of colon cancer: Imaging features and role in management. Radiographics 2000; 20: 419–30. 75. Iyer RB, Silverman PM, Dubrow RA, Charnsan, Gave C. Imaging in the diagnosis, staging, and follow-up of colorec- tal cancer. AJR Am J Roentgenl 2002; 179: 3–13. 76. Balfe D, Semin M. Colorectal cancer. In: Husband JES, Reznek RH, eds. Imaging in oncology. Oxford, UK: Isis Medical Media, 1998: 129–50. 77. Thoeni RF. Colorectal cancer: radiologic staging. Radiol Clin North Am 1997; 35: 457–85. 78. Balthazar EJ, Megibow AJ, Hulnick D, Naidich DP. Carcinoma of the colon: detection and preoperative staging by CT. AJR Am J Roentgenol 1988; 150: 301–6. 79. Earls JP, Colon-Negron E, Dachman AH. Colorectal carci- noma in young patients: CT detection of an atypical pattern of recurrence. Abdom Imaging 1994; 19: 441–5. 80. Freeny PC, Marks WM, Ryan JA, Bolen JW. Colorectal carcinoma evaluation with CT: preoperative staging and detection of postoperative recurrence. Radiology 1986; 158: 347–53. 81. Gazelle GS, Gaa J, Saini S, Shellito P. Staging of colon car- cinoma using water enema CT. J Comput Assist Tomogr 1995; 19: 87–91. 1 improved outcomes in colon and rectal surgery 82. Thompson WM, Halvorsen RA, Foster WL Jr, Roberts L, Gibbons R. Preoperative and postoperative CT staging for rectosigmoid carcinoma. AJR Am J Roentgenol 1986; 146: 703–10. 83. Acunas B, Rozanes I, Acunas G et al. Preoperative CT stag- ing of colon carcinoma (excluding the rectosigmoid region). Eur J Radiol 1990; 11: 150–3. 84. Zerhouni EA, Rutter C, Hamilton SR et al. CT and MR imaging in the staging of colorectal carcinoma: report of the Radiology Diagnostic Oncology Group II. Radiology 1996; 200: 443–51. 85. Ko GY, Ha HK, Lee HJ et al. Usefulness of CT in patients with ischemic colitis proximal to colonic cancer. AJR 1997; 168: 951–6. 86. Glotzer DJ, Gpihl BG. Experimental obstructive colitis. Arch Surg 1966; 92: 1–8. 87. Hurwitz A, Khafif RA. Acute necrotizing colits proximal to obstructing neoplasms of the colon. Surg Gynec Obstet 196; 111; 749–52. 88. Milar DM. Colitis and antecedent carcinoma. Dis Colon Rectum 1965; 8: 243–7. 89. Ganchrow MI, Clark JF, Benjamin HG. Ischemic colitis proximal to obstructing carcinoma of the colon: report of a case. Dis Colon Rectum 1971; 14: 38–42. 90. Saito K, Shimizu H, Yokoyama T et al. Ischemic enterocolits without arterio-occlusive lesion. Acta Pathol Jpn 1983; 33: 249–56. 91. Feldman PS. Ulcerative disease of the colon proximal to partially obstructive lesions. Dis Colon Rectum 1975; 18: 601–12. 92. Haligan MS, Saunders BP, Thomas BM, Philips RKS. Ischemic colitis in association with sigmoid carcinoma: a report of two cases. Clin Radiol 1994; 49: 183–4. 93. Yeung KW, Kuo YT, Huang CL, Wu DK, Liu GC. Inflammatory/infectious diseases and neoplasms of colon: evaluation with CT. Clin Imaging 1998; 22: 246–51. 94. Balfe D, Semin M. Colorectal cancer. In: Husband JES, Reznek RH, eds. Imaging in oncology. Oxford, UK: Isis Medical Media, 1998: 129–50. 95. Thoeni RF. Colorectal cancer: radiologic staging. Radiol Clin North Am 1997; 35: 457–85. 96. Inaba Y, Arai Y, Kanematsu M et al. Revealing hepatic metasta- ses from colorectal cancer: value of combined helical CT dur- ing arterial portography and CT hepatic arteriography with a unified CT and angiography system. AJR 2000; 174: 955–61. 97. Valls C, Andía E, Sánchez A et al. Hepatic metastases from colorectal cancer: preoperative detection and assessment of resectability with helical CT. Radiology 2001; 218: 55–60. 98. Pihl E, Hughes ES, McDermott FT, Milne BJ, Price AB. Disease-free survival and recurrence after resection of col- orectal carcinoma. J Surg Oncol 1981; 16: 333–41. 99. Thoeni RF, Rogalla P. CT for the evaluation of carcinomas in the colon and rectum. Semin Ultrasound CT MR 1995; 16: 112–26. 100. Finlay IG, Meek DR, Gray HW, Duncan JG, McArdle CS. Incidence and detection of occult hepatic metastases in col- orectal carcinoma. Br Med J 1982; 284: 803–5. 101. Desch CE, Benson AB 3rd, Somerfield MR et al. American Society of clinical oncology. Colorectal cancer surveillance: 2005 update of an American Society of clinical oncology practice guideline. J Clin Oncol 2005; 23: 8512–9. 102. Mutch MG, Birnbaum EH, Menias CO. ASCRS Textbook of Colon and Rectal Surgery, Chapter 6. New York: Springer- Verlag, 2006: 90. 103. Dobrin PB, Gully PH, Greenlee HB et al. Radiologic diag- nosis of an intra-abdominal abscess. Do multiple test help? Arch Surg 1986; 121: 41–6. 104. Aronberg DJ, Stanley RJ, Levitt RG et al. Evaluation ofab- dominal abscess with computed tomography. J Comput Assist Tomogr 1978; 2: 384–7. 105. Callen PW. Computed tomographic evaluation of abdomi- nal and pelvic abscesses. Radiology 1997; 131: 171–5. 106. Halber MD, Daffner RH, Morgan CL et al. Intraabdominal abscess: current concepts in radiologic evaluation. AJR Am J Roentgenol 1979; 133: 9–13. 107. Koehler PR, Moss AA. Diagnosis of intra-abdominal and pelvic abscesses by computerized tomography. JAMA 1980; 244: 49–52. 108. Jaques P, Mauro M, Safrit H et al. CT features of intraab- dominal abscesses: predicition of successful percutaneous drainage. AJR Am J Roentgenol 1986; 146: 1041–5. 109. Sandrasegaran K, Lall C, Rajesh A et al. Distinguishing gelatin bioabsorbable sponge and postoperative abdom- inal abscess on CT. AJR Am J Roentgenol 2005; 184: 475–80. 110. Young ST, Paulson EK, McCann RL, Baker ME. Appearance of oxidized cellulose (Surgicel) on postoperative CT scans: similarity to postoperative abscess. AJR Am J Roentgenol 1993; 160: 275–7. 111. Sheward SE, Williams AG Jr, Mettler FA Jr et al. CT appear- ance of surgically retained towel (gossypiboma). J Comput Assist Tomogr 1986; 10: 343–5. 112. Safriel Y, Zinn H. CT pulmonary angiography in the detec- tion of pulmonary emboli: a meta-analysis of sensitivities and specificities. Clin Imaging 2002; 26: 101–5. 113. Qanadli SD, Hajjam ME, Mesurolle B et al. Pulmonary embolism detection: prospective evaluation of dual-section helical CT versus selective pulmonary arteriography in 157 patients. Radiology 2000; 217: 447–55. 114. Winer-Muram HT, Rydberg J, Johnson MS et al. Suspected acute pulmonary embolism: evaluation with multi-detector row CT versus digital subtraction pulmonary arteriography. Radiology 2004; 233: 806–15. 115. Stein PD, Fowler SE, Goodman LR et al. Multidetector com- puted tomography for acute pulmonary embolism. N Engl J Med 2006; 354: 2317–27. 116. Remy-Jardin M, Pistolesi M, Goodman LR et al. Management of suspected acute pulmonary embolism in the era of CT angiography: a statement from the Fleischner Society. Radiology 2007; 245: 315–29. 117. Hull RD, Raskeb GE, Coates G, Panju AA, Gill GJ. A new non-invasive management strategy for patients with sus- pected pulmonary embolism. Arch Intern Med 1989; 149: 2549–55. 1 limitations of colorectal imaging studies 118. Katz DS, Loud PA, Bruce D et al. Combined CT venogra- phy and pulmonary angiography: a comprehensive review. RadioGraphics 2002; 22(Spec Issue): S3–S19. 119. Garg K, Kemp JL, Russ PD, Baron AE. Thromboembolic disease: variability of interobserver agreement in the inter- pretation of CT venography with CT pulmonary angiogra- phy. AJR Am J Roentgenol 2001; 176: 1043–7. 120. Loud PA, Katz DS, Bruce D, Klippenstein DL, Grossman ZD. Deep venous thrombosis with suspected pulmonary embolism: detection with combined CT venography and pulmonary angiography. Radiology 2001; 219: 498–501. 121. Cham MD, Yankelevitz DF, Henschke CI. Thromboembolic disease detection at indirect CT venography versus CT pulmonary angiography. Radiology 2005; 234: 591–4. 122. Taffoni MJ, Ravenel JG, Ackerman SJ. Prospective compari- son of indirect CT venography versus venous sonography in ICU patients. AJR Am J Roentgenol 2005; 185: 457–62. 123. Balthazar EJ, Megibow AJ, Siegel SE, Birnbaum BA. Appendicitis: prospective evaluation with high-resolution CT. Radiology 1991; 180: 21–4. 124. Rao PM, Rhea JT, Novelline RA et al. Helical CT technique for the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination. Radiology 1997; 202: 139–44. 125. Wijetunga R, Tan BS, Rouse JC, Bigg-Wither GW, Doust BD. Diagnostic accuracy of focused appendiceal CT in clinically equivocal cases of acute appendicitis. Radiology 2001; 221: 747–53. 126. Birnbaum BA, Jeffrey RB Jr. CT and sonographic evaluation of acute right lower quadrant abdominal pain. AJR 1998; 170: 361–71. 127. Malone AJ Jr, Wolf CR, Malmed AS, Melliere BF. Diagnosis of acute appendicitis: value of unenhanced CT. AJR 1993; 160: 763–6. 128. Lane MJ, Mindelzun RE. Appendicitis and its mimickers. Semin Ultrasound CT MR 1999; 20: 77–85. 129. Friedland JA, Siegel MJ. CT appearance of acute appendicitis in childhood. AJR 1997; 168: 439–42. 130. Levine CD, Aizenstein O, Lehavi O, Blachar A. Why we miss the diagnosis of appendicitis on abdominal CT: evaluation of imaging features of appendicitis incorrectly diagnosed by CT. AJR Am J Roentgenol 2005; 184: 855–9. 131. Rao PM, Rhea JT, Novelline RA et al. Helical CT scan- ning with contrast material administered only through the colon for imaging suspected appendicitis. AJR 1997; 169: 1275–80. 132. Rao PM, Rhea JT, Novelline RA. Focused, helical appen- diceal CT: technique and interpretation. Emerg Radiol 1997; 4: 268–75. 133. Pickhardt PJ, Levy AD, Rohrmann CA Jr, Kende AI. Primary neoplasms of the appendix: radiologic spectrum of disease with pathologic correlation. Radiographics 2003; 23: 645–62. 134. Madwed D, Mindelzun R, Jeffrey RB Jr. Mucocele of the appendix: imaging findings. AJR 1992; 159: 69–72. 135. Zissin R, Gayer G, Kots E et al. Imaging of mucocele of the appendix with emphasis on the CT findings: a report of 10 cases. Clin Radiol 1999; 54(12): 826–32. 136. Lim HK, Lee WJ, Kim SH et al. Primary mucinous cysta- denocarcinoma of the appendix: CT findings. AJR Am J Roentgenol 1999; 173(4): 1071–4. 137. Pickhardt PJ, Levy AD, Rohrmann CA Jr et al. Non- Hodgkin’s lymphoma of the appendix: clinical and CT findings with pathologic correlation. AJR Am J Roentgenol 2002; 178: 1123–7. 138. Pelage JP, Soyer P, Boudiaf M et al. Carcinoid tumors of the abdomen: CT features. Abdom Imaging 1999; 24: 240–5. 139. Dudiak KM, Johnson CD, Stephens DH. Primary tumors of the small intestine: CT evaluation. AJR Am J Roentgenol 1989; 152: 995–8. 140. Maglinte DT, Herlinger H. Small bowel neoplasms. In: Herlinger H, Maglinte DT, Birnbaum BA, eds. Clinical imaging of the small intestine. New York, NY: Springer- Verlag, 2001: 377–438. 141. Horton KM, Eng J, Fishman EK. Normal enhancement of the small bowel: evaluation with spiral CT. J Comput Assist Tomogr 2000; 24: 67–71. 142. Cockey B, Fishman E, Jones B. Computed tomography of abdominal carcinoid tumor. J Comput Assist Tomogr 1985; 9: 38–42. 143. Buckley JA, Jones B, Fishman EK. Small bowel cancer: imag- ing features and staging. Radiol Clin North Am 1997; 35: 381–402. 144. Koehler RE. Small bowel neoplasms. In: Freeny PC, Stevenson GW, eds. Margulis and Burhenne’s alimentary tract radiology. St. Louis, MO: Mosby, 1994: 627–48. 145. Pantongrag-Brown L, Buetow PC, Carl NJ, Lichtenstein JE, Buck JL. Calcification and fibrosis in mesenteric carcinoid tumor: CT findings and pathologic correlation. AJR 1995; 164: 387–91. 146. Seigel RS, Kuhns LR, Borlaza GS, McCormick TL, Simmons JL. Computed tomography and angiography in ileal car- cinoid tumor and retractile mesenteritis. Radiology 1980; 134: 437–40. 147. Bressler EL, Alpern MB, Glazer GM, Francis IR, Ensminger WD. Hypervascular hepatic metastases: CT evaluation. Radiology 1987; 162: 49–51. 148. McDermott VG, Low VH, Keogan MT et al. Malignant melanoma metastatic to the gastrointestinal tract. AJR Am J Roentgenol 1996; 166(4): 809–13. 149. Byun JH, Ha HK, Kim AY et al. CT findings in periph- eral T-cell lymphoma involving the gastrointestinal tract. Radiology 2003; 227: 59–67. 150. Tamm EP, Fishman EK. Ct appearance of acute abdomen as initial presentation in lymphoma of the large and small bowel. Clin Imaging 1996; 20: 21–5. 151. Levy AD, Remotti HE, Thompson WM et al. Gastrointestinal stromal tumor: radiologic features with pathologic correla- tion. Radiographics 2003; 23: 283–304. 152. Pear BL. Pneumatosis intestinalis: A review. Radiology 1998; 207: 13–9. 153. Gore RM, Miller FH, Pereles FS, Yaghamai V, Berlin JW. Helical CT in the evaluation of the acute abdomen. AJR Am J Roentgenol 2000; 174: 901–13. . enhancement indicates active terminal ileitis. (a) (b) 1 improved outcomes in colon and rectal surgery extension (Figure 11.55), and has an advantage over CT in the evaluation of tumoral invasion. metabolic activity (including carcinoid and mucinous adenocarcinoma) have a higher likelihood of a false-negative result.(261, 262) Gastrointestinal Scintigraphy Nuclear medicine scintigraphy is. metastasectomy.(251) Endoluminal Ultrasound Endoluminal ultrasound’s (EUS) impact on the workup for col- orectal cancer continues to expand. Transrectal US appears to be the most accurate imaging modality in determining