~

FORUMS .-~~. ~- -. Radiology Consultants:

IN.-_GASTROINTESTINAL ~._.---

Editors: WALTER

WYLIE

J.

HOGAN,

ROENTGENOLOGY

J. DODDS, MD. AND HENRY L. GOLDBERG, MD MD, ROBERT K. OCKNER, MD, AND RICHARD L. WECHSLER, MD

Endoscopic Retrograde Cholangiopancreatography (ERCP): Radiographic Technique HENRY

I. GOLDBERG, CHARLES

MD, MARCIA A. ROHRMANN,

K. BILBAO, MD, EDWARD T. STEWART, MD, and ALBERT A. MOSS, MD

The diagnostic value of endoscopic retrograde cholangiopancreatography (ERCP) is fully exploited only if the radiographs obtained are of excellent quality. Careful attention to factors such as type of fluoroscopic equipment, small focal spot, and adequate preliminary films are an important requisite. Using fluoroscopy to locate the ampullary region and to monitor the extent of filling of pancreatic and biliary ductal system during contrast injection speeds completion of the study and helps prevent complications. Performing ERCP with attention to patient positioning and awareness of possible need for delayed radiographs also enhances its diagnostic capability. EQUIPMENT

In order to obtain suitable roentgenograms during ERCP the radiographic suite should contain quality x-ray equipment. A three-phase generator with a high milliampere capability and a small focal spot (0.3-0.6 mm) x-ray tube are virtually a necessity. Exposure time should be as short as possible (0.10 set or less). Using a high milliampere setting, short exposure, and high voltage (100-120 kV). quality radiographs can be made which show no lack of clarity ~ due to~~motion. An alternate method of obtaining From the Departments of Radiology. University of California School of Medicine. San Francisco (HIGJAM), University of Oregon Medical Center, Portland (MKR), Medical College of Wisconsin, Milwaukee County General Hospital, Milwaukee (ETS), and the Veterans Administration Hospital and the University of Minnesota, Minneapolis (CAR). Dr. Goldberg is supported. in part, by Research Career Development Award 5 K04 GM 70582 from the National Institute of General Medical Sciences. Address for reprints requests: Dr. Henry I. Goldberg, Department of Radiology. Room M-380, University of California School of Medicine, San Francisco, California 94143.

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MD,

short exposure at high kilovoltage is the use of highspeed screens and films. A radiographic table capable of being tilted from upright to a 15” headdown position is desirable to permit a full range of patient positioning. Typically the fluoroscopic unit has an image intensifier above the x-ray table and the x-ray tube beneath. A television monitor enables the radiologist and the endoscopist to observe ductal filling during contrast injection. In some circumstances, an overtable x-ray tube and remote control unit may be used instead of the standard fluoroscopic arrangement. The overhead tube of such units can be tilted to view opacified ducts at an angle, in some cases demonstrating areas that would otherwise be obscured by the fiberoptic endoscope. Because more radiation exposure occurs from the overhead tube than the conventional under-table tube, special shielding is necessary for working personnel. FLUOROSCOPIC

MONITORING

Before passing the endoscope, scout films of the upper abdomen are needed to show abnormal densities such as pancreatic and gallbladder calculi, or residual barium, as well as to determine proper xray exposure. Attempts to determine proper exposure after cannulation and injection of contrast material invariably result in delay and may compromise the study. Fluoroscopy by an experienced fluoroscopist is often helpful during positioning of the endoscope for cannulation, particularly for those inexperienced in cannulation. Fluoroscopic assistance generally saves time even for the expert endoscopist and minimizes trauma to the patient. Brief fluoroscopic exposures are used to check enDigestive

Diseases.

Vol. 21, No. 3 (March

1976)

CHOLANGIOPANCREATOGRAPHY

Fig 1. The tip of the side-viewing fiberoptic endoscope is seen in profile. The mirror (M) and tip deflector (E) produce this characteristic profile, which aids in determining which duodenal wall is being viewed (in this instance the lateral wall).

doscope position. The only times that fluoroscopic exposure should be extended are during duct filling or positioning of the patient for spot-filming. During fluoroscopy and filming the field should always be optimally coned in order to reduce radiation exposure to the patient, working personnel, and fiberoptic instrument. The side-viewing endoscope has a characteristic profile that permits fluoroscopic identification of the mirror and the cannula elevator (Figure 1). Thus, a Digestive Diseases, Vol. 21, No. 3 (March 1976)

fluoroscopic check quickly determines whether the mirror shows the medial or the lateral duodenal wall. It is essential to perform fluoroscopy during all contrast injections to monitor whether and to what extent the duct is being filled. Contrast agent accumulating in the duodenum has an amorphous appearance in contradistinction to the linear horizontal configuration of the pancreatic duct or the vertically oriented common bile duct. Early recognition

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GOLDGERG

ET AL

Fig 2. The apparent obstruction of the midportion of the main pancreatic duct is due to an air lock. Air, inadvertently injected during cannulation of the pancreatic duct, is visible in the distal part of the duct (arrows).

Fig 3, A parenchymal blush (arrows) has been produced by injection of contrast material with too much pressure. Note the fine, homogeneous appearance of the parenchyma. The main pancreatic duct and its branches are normal. Only the parenchymal blush in the head of the pancreas could be seen on the television monitor.

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Digestive Diseases, Vol. 21, No. 3 (March 1976)

CHOLANGIOPANCREATOGRAPHY

Fig 4. (Above) The most distal portion of the common bile duct was filled with contrast material when fluoroscopy was performed with the patient in the prone position. (Below) By placing the patient in the supine position, without injecting additional contrast material, the distal common duct was seen. Digestive Diseases, Vol. 21, No. 3 (March 1976)

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G O L D G E R G ET AL

Fig 5. (Above) The cannula is inserted several centimeters into the common bile duct. The ampullary canal is not opacified. (Below) With the cannula withdrawn, the ampullary canal (open arrow) is well seen, and a small stone (solid arrow) is identified in the distal duct.

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Digestive Diseases, Vol. 21, No. 3 (March 1976)

CHOLANGIOPANCREATOGRAPHY

Fig 6. Thirty minutes after the cannula was withdrawn from the pancreatic duct, a large amount of contrast material still resided in the dilated, tortuous, main pancreatic duct and its branches. This is the typical radiographic appearance of chronic pancreatitis. A dense blush is present in the head of the pancreas.

of intraduodenal contrast is important to avoid unnecessary accumulations of contrast material that m a y obscure the ducts. During ductal injection, areas of nonfilling need to be recognized so that particular attention can be focused on the area where filling ceases. Air bubbles or air locks can produce pseudo-obstruction of the pancreatic (Figure 2) or biliary ducts. These types of obstruction may be distinguished from true obstruction if no tapering or widening of the duct is seen. When it is not clear whether or not an air lock is present, further careful filling is indicated. Altering patient position may move the air from one segment to another. Another important function of fluoroscopic monitoring is to avoid ductal overfilling. Excessive injection pressure or over-filling of the pancreatic Digestive Diseases, Vol. 21, No. 3 (March 1976)

ducts causes a parenchymal blush (Figure 3). This blush represents contrast agent in the acini and possibly in the interstitium. Although a blush may be seen in normal patients as a result of over-filling, it is commonly seen in patients with acute or chronic pancreatitis (1, 2), even when the injection force is kept minimal. Every effort should be made to avoid a parenchymal blush because over-filling of pancreatic ducts may lead to acute pancreatitis. For this reason, a radiologist should carefully fluoroscope the pancreas during contrast injection so that the injection can be stopped ifparenchymal blush is seen. PATIENT POSITIONING After contrast material has been injected, the patient's position generally needs to be changed.

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GOLDBERG ET AL

Fig 7. Thirty minutes after the cannula was withdrawn from the common bile duct, a full column of contrast material was present. The ampullary canal was narrowed (arrow). This narrowing was noted on several radiographs obtained during the 30-min period. The patient had undergone a sphincter dilatation at the time of cholecystectomy one year before this study. Subsequent common duct surgery demonstrated fibrosis of Oddi's sphincter.

Because heavy contrast material gravitates to the dependent ducts, appropriate patient positioning is an essential part of ductal radiography. Filling of the pancreatic ducts is first attempted with the patient prone. The pancreatic duct can often be filled entirely in this manner. A dilated, tortuous duct of patients with chronic pancreatitis, however, may not fill completely in this position. In this instance, the patient is placed left side down so that gravity favors filling of the distal pancreatic duct. During filling of the biliary ducts with the patient in the prone position, contrast material will preferentially flow from the common hepatic duct into the left hepatic duct. Filling of the posterior branches of the right duct as well as the distal part of the common bile duct (CBD) often does not occur until the

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patient is placed supine (Figure 4A and B). If a stricture is present in the extrahepatic ductal system, the patient may need to be positioned supine to favor filling past the stricture. Tilting the head of the x-ray table downward is also helpful. In some cases, a lateral view is needed to distinguish the ampullary region from a contrast-filled gallbladder that obscures the ampulla on the frontal view. The lateral view is particularly useful for evaluating a dilated CBD in a patient with previous CBD surgery, because short strictures may be hidden in the frontal view. FILMING

Multiple radiographs are essential for adequately demonstrating ductal anatomy and pathology. Both Digestive Diseases, Vol. 21, No. 3 (March 1976)

CHOLANGIOPANCREATOGRAPHY

: :

Fig 8. A pseudocyst that filled with contrast material during injection of the main pancreatic duct was still filled 3 hr later. The patient subsequently developed shaking, chills, and septicemia and died the next day from septic shock. Because of such complications, pseudocysts should not be overfilled with contrast material. (Courtesy of Dr. Ralph Bernstein, Highland-Alameda Hospital, Alameda, California).

full films and 4-on-1 spot-films should be obtained. Small spot-films alone do not allow complete orientation of the biliary and pancreatic ductal systems. Some workers have found the 105-mm camera particularly suitable for ERCP work. Films should be obtained while the contrast agent is being injected and also during and after removal of the cannula so that the ampullary canal can be seen (Figure 5A and

B). When ductat obstruction is suspected, radiographs should be made at 15 and at 30 min after the cannula has been withdrawn and, if necessary, still later. If, after 30 min, contrast material is still in the dilated duct, the presence of an obstruction or chronic pancreatitis must be considered (Figure 6). Normal emptying time of the main pancreatic duct (MPD) has been reported to be 10-20 sec (3), 2 Digestive Diseases, Vol. 21, No. 3 (March 1976)

min (4), and 4 min (5). In our experience, emptying times of 15-30 min for the MPD can occur in chronic pancreatitis, pancreatic carcinoma, and occasionally in aged normal patients with dilated pancreatic ducts. We have observed that the CBD usually empties within 15 min after cannula withdrawal. One group of investigators (2), however, reports that it is not unusual to see contrast material 1 hr after injection, particularly when the gallbladder had been filled. We have found the emptying time for the common bile duct to be 30-60 minutes with various obstructing lesions, including benign stricture, stone, tumor, and papillary stenosis (Figure 7). At present, however, controversy exists and emptying times have yet to be established. If the gallbladder fills, routine, upright, spot films sometimes reveal unsuspected calculi. The upright

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GOLDBERG ET AL position is also useful in differentiating a common bile duct stone from an air bubble because air bubbles rise whereas stones tend to gravitate to the distal part of the common duct.

CONTRAST MATERIAL Sterile, water-soluble iodinated contrast material should be available both in undiluted form (50-75% iodine solution) and diluted form (half and half with saline). The concentrated material is used for the initial injection so that the ducts can be identified. It can also be used to study the entire, nondilated pancreatic duct. If the MPD is dilated or if the CBD is also to be filled, or both, it is best to use diluted contrast material so that stones or filling defects are not obscured by contrast material that is overly dense. The flow properties of the water-soluble contrast are improved if it is placed in a warm water bath prior to use. The amount of contrast agent used depends upon whether or not the ductal system is dilated. The normal pancreatic duct can be filled with as little as 2-5 ml and the normal biliary tree with 812 ml of contrast. If the gallbladder fills, as much as 50-80 ml may be necessary to do the study. The amount of pressure needed to inject the contrast material should be sufficient to fill the ducts, but not to over-fill them. A slow, constant injection provides more even filling than short, rapid spurts. The appearance of a pancreatic parenchymal blush on the television monitor indicates that the injection has been too forceful. A recent study (6) using a simple water manometer to determine injection pressure suggests that a pressure of 110 mm HzO is adequate pressure to fill the pancreatic duct and 80100 mm H~) pressure adequate for the CBD. Overfilling of the pancreas can occur inadvertently from repeated injections into the already filled pancreatic ducts, as sometimes happens during attempts to cannulate the CBD after the pancreas has already been studied. Pseudocysts should not be filled with contrast medium. The size and extent of the pseudocyst can be seen by injecting a small amount of contrast agent and using positioning to outline the cyst walls. Over-filling of pseudocysts may lead to rupture, septicemia (7), and even death (Figure 8). Caution should also be exercised when filling a duct that has a stricture. Although it is important to outline the extent of a stricture, attempted filling of the entire duct distal to the obstruction may well lead to septi-

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cemia, particularly in CBD obstruction. The presence of contrast material in the kidney is a relatively common finding after retrograde cholangiopancreatography, particularly on late films. Of 27 consecutive patients undergoing ERCP at the University of California San Francisco, 10 demonstrated renal excretion of contrast material. None developed pancreatitis. At the University of Minnesota, Rohrmann noted renal opacification in 26% of 72 patients in whom both ductal systems were seen (8). A report by Bilbao et al (7) suggests renal opacification has predictive value. Contrast material was seen in the kidneys in 7 of 75 patients. Each of these 7 patients had multiple pancreatic injections and exhibited acinar filling. 5 of the 7 developed postprocedure pancreatitis. They were the only ones to develop pancreatitis in the entire series. The fact that contrast material is seen in the kidneys after retrograde injection into the biliary or pancreatic duct system indicates that iodinated contrast material, in some instances, does reach the systemic circulation. Any patient known to react to intravenously administered contrast material, therefore, should not be considered exempt from a possible allergic reaction when the contrast material is administered retrograde into the biliary or pancreatic ducts. REFERENCES 1. Kasugai TK, Kuno N, Kizu M, Kobayashi S, Hattori K: Endoscopic pancreatocholangiography II: The pathological endoscopic pancreatocholangiogram. Gastroenterology 63:227-234, 1972 2. Kasugai TK, Kuno N, Kobayashi S, Hattori K: Endoscopic pancreatocholangiography I: The normal endoscopic pancreatocholangiogram. Gastroenterology 63:217-226, 1972 3. Ogoshi K, Niwa M, Hara Y, Nebel OT: Endoscopic pancreatocholangiography in the evaluation of pancreatic and biliary disease. Gastroenterology 64:210-216, 1973 4. Weiss HD, Anacker H, Wiesner W, Rupp N: Duodenoscopic pancreatography. Radiology 107:333-339, 1973 5. Okuda K, Someya N, Goto A, Kunisaki T, Emura T, Yasumoto M, Shimokawa Y: Endoscopic pancreato-cholangiography: A preliminary report on technique and diagnostic significance. Am J Roentgenol 117:437-445, 1973 6. Kasugai T, Kuno N, Kizu M: Manometric endoscopic retrograde pancreatocholangiography: Technique, significance, and evaluation. Am J Dig Dis 19:485-502, 1974 7. Bilbao MK, Dotter CT, Lee T, Katon RM: Complications of ERCP. Am J Dig Dis (in press) 8. Rohrmann CA, Silvis SE, Vennes JA: Evaluation of the endoscopic pancreatogram. Radiology 113:297-304, 1974 9. Nelson JA, Benet JZ, Goldberg HI: Absorption of iodipamide from the biliary system of the rabbit. J Pharm Pharmacol 24:993-995, 1972 (letters to the editor) Digestive Diseases, Vol. 21, No. 3 (March 1976)

Endoscopic retrograde cholangiopancreatography (ERCP): radiographic technique.

~ FORUMS .-~~. ~- -. Radiology Consultants: IN.-_GASTROINTESTINAL ~._.--- Editors: WALTER WYLIE J. HOGAN, ROENTGENOLOGY J. DODDS, MD. AND HENR...
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