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Demonstration of pancreatic parenchyma by digital subtraction techniques during endoscopic retrograde cholangiopancreatography
ChnicalRadtology (1985) 36,405-407 © 1985Royal College of Radiologists
000%9260/85/470405502.00
Demonstration of Pancreatic Parenchyma by Digital Subtraction Techniques during Endoscopic Retrograde Cholangiopancreatography M. I. LAVELLE, N. P. TAIT, T. WALSH*, D. ALDERSON* and C. O. RECORD*
Departments of Radiology and *Gastroenterology, Royal Victoria Infirmary, Newcastle upon Tyne
This paper reports the feasibility of using digital subtraction angiography techniques during endoscopic retrograde cholangiopancreatography to obtain greater detail of pancreatic structure. The pancreatic duct was filled in 23 of 27 cases attempted and in 17 cases parenchymal detail was obtained. Filling defects due to neoplasm were clearly defined and the changes of chronic pancreatitis visualised. The technique seems valuable for small lesions but may carry a higher risk of producing pancreatitis.
The extent and nature of pathology in the pancreatic parenchyma can be shown using non-ionic contrast media during cndoscopic retrograde cholangiopancreatography (ERCP) (Twomey et al., 1982). The aim of the present study was to see if this technique could be improved by using digital subtraction angiography (DSA) equipment which is sensitive to differences in contrast of 1%. EQUIPMENT Radiographic This comprised a Picker International Digicon 212 with a floor-wall mounted X-ray tube and image intensifier system on an L / U arm support. The intensifier is a 30/22/15 cm triple field, high-resolution unit with an Anodica 100 mm cut film camera attached. A 100 kW Vector microprocessor generator provides the power. The computer is a Dec LSI 11/23, storing information in digital form on a 474 Mbyte Winchester disc. Postprocessing facilities include re-registration in fractions down to 0.01 pixel, frame averaging, magnification and image enhancement. Selected images are transferred to film via a Matrix 7 multi-imager. Endoscopic A standard Fujinon D U O - X L side viewing duodenoscope was used for these studies. PATIENTS AND METHODS Twenty-seven patients referred for ERCP with a suspected pancreatic lesion were studied. Endoscopic 35
cannulation was carried out in the standard manner (Cotton and Williams, 1983). Duodenal hypotonia was achieved with intravenous injections of hyoscine N-butylbromide (Buscopan, Boehringer Ingelheim) 40 mg supplemented by glucagon 1 mg if required. In two cases of suspected insulinoma, only Buscopan was administered. The contrast medium used was iopamidol 370 (Niopam, Bracco), initially diluted to half strength but increased to 75% strength when the images proved inadequate. Once cannulation of the papilla of Vater had been achieved, a small test injection was made, sufficient only to indicate which duct was filling. If the pancreatic duct was outlined, a test exposure followed by a series of exposures at a rate of 1/s was initiated and the hand injection of contrast medium started after allowing at least two exposures for masking. The images were displayed in subtracted form as they were taken. In the first four cases injection and exposures were terminated as soon as complete filling of the main pancreatic and side radicles was evident. In subsequent cases injection continued until significant parenchymal filling was observed unless a contraindication, such as a dilated pancreatic duct, was discovered. With one exception, discussed later, only one injection producing parenchymal filling was made. Immediately after the digital run, routine radiographs were taken using the Anodica camera. After the procedure, patients were monitored for clinical evidence of acute pancreatitis. Serum amylase was measured after 4 h and 24 h and, if elevated,was measured daily until normal. RESULTS Cannulation was successful in 26 cases (96%), failure occurring in one case where the papilla lay in a diverticulum. The pancreatic duct alone was filled in 11 cases (42%), the biliary tract in three cases (11.5%) and both ducts in 12 cases (46%). Attempts to fill the biliary tree were not continued if the clinical indication was for a pancreatic study only. In the first four patients, faint parenchymal filling was seen when post-processing. Two of these cases had a normal pancreatic duct and two showed changes of chronic pancreatitis. These studies demonstrated that adequate subtraction is easily obtained, giving detail of the pancreatic duct system comparable to a standard radiograph (Fig. 1). Good parenchymal filling was obtained in 17 of the subsequent examinations. A normal gland, characterised by smooth, even filling of the parenchyma (Fig. 2), was found in seven patients. Six showed uneven
406
CLINICAL RADIOLOGY
(a) (b) Fig. 1 - Comparison of a normal pancreatic duct systcm shown (a) on a standard radiograph and (b) using digital subtraction technique.
g.
Fig. 2 - Normal gland showing smooth filling ol parenchyma.
/
/
s
Fig. 3 - Uneven parenchymal filling in the tail of a pancreas mdacatmg chronic pancreatitis.
Fig. 4 - Well defined edge (arrowed) of parenchymal filling defect due to carcinoma of thc body of the pancreas.
staining indicating chronic pancreatitis (Fig. 3). A filling defect (Fig. 4) suggestive of malignant neoplasm was found in three patients and the diagnosis was subsequently confirmed by surgery or biopsy. These findings prompted a study of a patient with a suspected insulinoma where ultrasound, angiography and computed tomographic angiography had produced inconclusive results. On the first injection the subtracted images showed a filling defect in the region of the uncinate process about 1 cm across, as judged by the diameter of the endoscope, which is 13 mm. In view of the importance of precise location, a second injection was made and the findings confirmed. The tumour was removed at surgery and histological confirmation obtained. An attempt to demonstrate an insulinoma in a second case was unsuccessful as only the bile duct could be cannulated. In three cases (one of chronic pancreatitis, one unexplained abdominal pain and one suspected insulinoma) only a normal biliary tract could be shown. Of the remaining two cases, one showed dilated pancreatic and
DEMONSTRATION OF PANCREATIC PARENCHYMA BY DSA DURING ERCP
biliary ducts suggestive of an ampullary lesion and the other showed gall-stones in the common bile duct with a normal pancreatic duct. Serum amylase levels in six cases remained within our normal range (70-300 U/litre); 18 showed a brisk but transient hyperamylasaemia, maximum at 4 h and falling to normal within 2-3 days. Two patients developed clinical evidence of mild acute pancreatitis. DISCUSSION The use of DSA techniques in ERCP has been reported by Weiss and Gmelin (1983). One of the problems encountered was artefacts due to patient movement as the result of sedation preventing patient co-operation. We were able to overcome this problem by using the improved post-processing techniques now available and by taking at least two mask images prior to injection. These were invariably in a different phase of respiration and the one most appropriate to the rest of the run was used. Also, further masks to show the parenchyma of the gland can be made from the images where only the main duct is filled. Until the advent of non-ionic contrast media, demonstration of the pancreatic parenchyma during ERCP was avoided because of the risk of pancreatitis (Cotton, 1977). Yoshimoto et al. (1981) attempted to solve this problem by combining sodium and meglumine diatrizoate or sodium iothalamate with polyoxyethylene hydrogenated castor oil, a non-ionic surfactant, to increase parenchmyal staining without excessive injection pressure. They were able to show uniform smooth staining of the parenchyma in a normal gland, uneven staining and irregular contour in chronic pancreatitis and a parenchmyal filling defect in carcinoma. The increased sensitivity of DSA equipment, enabling it to detect a 1% difference in contrast, suggested that improved visualisation of the parenchyma would be achieved with a non-ionic medium alone, based on the method reported by Twomey et al. (1982). The study confirms that this is possible but that it may carry a higher risk. Acute pancreatitis is a recognised complication of ERCP (Cotton, 1977), occurring in about 1% of routine cases performed in our centre, a frequency similar to that found in other experienced units (Bilbao et al., 1976). Two patients in this study developed pancreatitis, an incidence of 7.3% which is comparable with early ERCP studies (Ruppin et al., 1974). One case, the patient with an insulinoma, had a mild episode lasting about 6 h with serum amylase reaching a peak of 6000
407
U/litre by 4 h and falling to normal within 48 h. This patient had two parenchymal injections, the decision to repeat the injection being taken after balancing the risk of complications against the need to confirm localisation. The second case occurred in a patient with unexplained abdominal pain who showed a normal pancreas. Again, the symptoms settled rapidly on conservative treatment, the amylase returning to normal in 72 h. It is worth noting that five of the six cases where the amylase remained within the normal range were in the parenchymal filling group. Against the increased risk of acute pancreatitis must be set the value of detecting small parenchymal lesions such as an insulinoma. Increasing experience with this technique may reduce the complication rate to that of the standard ERCP; monitoring the injection pressures required to produce parenchymal filling using the technique described by Kasugai et al. (1974) may prove helpful. In conclusion, digital imaging of the parenchyma of the pancreas during ERCP is feasible and can outline small parenchymal lesions as well as carcinoma and changes of chronic pancreatitis. However, using the techniques described in this study, we have found an increased risk of acute pancreatitis. Acknowledgements. We wish to acknowledge the Audio Visual Centre of the University of Newcastle upon Tyne for preparing the illustrations and Mrs K. J. Tunstall for typing the manuscript.
REFERENCES Bilbao, M. K., Dotter, C. T., Lee T. G & Katon, R. M. (1976). Complications of endoscopic retrograde cholangiopancreatography (ERCP). A study of 10,000 cases. Gastroenterology, 70, 314320. Cotton, P.B. (1977). Progress report. ERCP. Gut, 18, 316-341. Cotton, P. B. & Williams, C. B. (1983). Practical Gastrointestinal Endoscopy, pp. 62-68. Blackwell Scientific Publications, Oxford. Kasugai, T., Kuno, N. & Kizu, M. (1974). Manometric endoscopic retrograde pancreatocholangiography. American Journal of Digestive Diseases, 19, 485-501. Ruppin, H., Amon, R., Ett, W., Classen, M. & Demling, L. (1974). Acute pancreat~tis after endoscopic/radlologlcal pancreatography (ERP). Endoscopy, 6, 94-98. Twomey, B., Wilkins, R. A. & Levi, A. J. (1982). Pancreatic parenchymography using metrizamide (abstract). Gut, 23, 432. Weiss, H.-D. & Gmelin, E. (1983). Possibilities provided by digital subtraction angiography/digital subtraction radiography for improved visualization of the pancreas. Preliminary report. Contrast Media in Digital Radiography, Current Clinical Practice Series 12, pp. 343-345. Excerpta Medica, Amsterdam. Yoshimoto, S., Ohnishi, R., Dol, S. & Kawai, K. (1981). Endoscopic retrograde parenchymography. Radiology, 141,219-222.
000%9260/85/470405502.00
Demonstration of Pancreatic Parenchyma by Digital Subtraction Techniques during Endoscopic Retrograde Cholangiopancreatography M. I. LAVELLE, N. P. TAIT, T. WALSH*, D. ALDERSON* and C. O. RECORD*
Departments of Radiology and *Gastroenterology, Royal Victoria Infirmary, Newcastle upon Tyne
This paper reports the feasibility of using digital subtraction angiography techniques during endoscopic retrograde cholangiopancreatography to obtain greater detail of pancreatic structure. The pancreatic duct was filled in 23 of 27 cases attempted and in 17 cases parenchymal detail was obtained. Filling defects due to neoplasm were clearly defined and the changes of chronic pancreatitis visualised. The technique seems valuable for small lesions but may carry a higher risk of producing pancreatitis.
The extent and nature of pathology in the pancreatic parenchyma can be shown using non-ionic contrast media during cndoscopic retrograde cholangiopancreatography (ERCP) (Twomey et al., 1982). The aim of the present study was to see if this technique could be improved by using digital subtraction angiography (DSA) equipment which is sensitive to differences in contrast of 1%. EQUIPMENT Radiographic This comprised a Picker International Digicon 212 with a floor-wall mounted X-ray tube and image intensifier system on an L / U arm support. The intensifier is a 30/22/15 cm triple field, high-resolution unit with an Anodica 100 mm cut film camera attached. A 100 kW Vector microprocessor generator provides the power. The computer is a Dec LSI 11/23, storing information in digital form on a 474 Mbyte Winchester disc. Postprocessing facilities include re-registration in fractions down to 0.01 pixel, frame averaging, magnification and image enhancement. Selected images are transferred to film via a Matrix 7 multi-imager. Endoscopic A standard Fujinon D U O - X L side viewing duodenoscope was used for these studies. PATIENTS AND METHODS Twenty-seven patients referred for ERCP with a suspected pancreatic lesion were studied. Endoscopic 35
cannulation was carried out in the standard manner (Cotton and Williams, 1983). Duodenal hypotonia was achieved with intravenous injections of hyoscine N-butylbromide (Buscopan, Boehringer Ingelheim) 40 mg supplemented by glucagon 1 mg if required. In two cases of suspected insulinoma, only Buscopan was administered. The contrast medium used was iopamidol 370 (Niopam, Bracco), initially diluted to half strength but increased to 75% strength when the images proved inadequate. Once cannulation of the papilla of Vater had been achieved, a small test injection was made, sufficient only to indicate which duct was filling. If the pancreatic duct was outlined, a test exposure followed by a series of exposures at a rate of 1/s was initiated and the hand injection of contrast medium started after allowing at least two exposures for masking. The images were displayed in subtracted form as they were taken. In the first four cases injection and exposures were terminated as soon as complete filling of the main pancreatic and side radicles was evident. In subsequent cases injection continued until significant parenchymal filling was observed unless a contraindication, such as a dilated pancreatic duct, was discovered. With one exception, discussed later, only one injection producing parenchymal filling was made. Immediately after the digital run, routine radiographs were taken using the Anodica camera. After the procedure, patients were monitored for clinical evidence of acute pancreatitis. Serum amylase was measured after 4 h and 24 h and, if elevated,was measured daily until normal. RESULTS Cannulation was successful in 26 cases (96%), failure occurring in one case where the papilla lay in a diverticulum. The pancreatic duct alone was filled in 11 cases (42%), the biliary tract in three cases (11.5%) and both ducts in 12 cases (46%). Attempts to fill the biliary tree were not continued if the clinical indication was for a pancreatic study only. In the first four patients, faint parenchymal filling was seen when post-processing. Two of these cases had a normal pancreatic duct and two showed changes of chronic pancreatitis. These studies demonstrated that adequate subtraction is easily obtained, giving detail of the pancreatic duct system comparable to a standard radiograph (Fig. 1). Good parenchymal filling was obtained in 17 of the subsequent examinations. A normal gland, characterised by smooth, even filling of the parenchyma (Fig. 2), was found in seven patients. Six showed uneven
406
CLINICAL RADIOLOGY
(a) (b) Fig. 1 - Comparison of a normal pancreatic duct systcm shown (a) on a standard radiograph and (b) using digital subtraction technique.
g.
Fig. 2 - Normal gland showing smooth filling ol parenchyma.
/
/
s
Fig. 3 - Uneven parenchymal filling in the tail of a pancreas mdacatmg chronic pancreatitis.
Fig. 4 - Well defined edge (arrowed) of parenchymal filling defect due to carcinoma of thc body of the pancreas.
staining indicating chronic pancreatitis (Fig. 3). A filling defect (Fig. 4) suggestive of malignant neoplasm was found in three patients and the diagnosis was subsequently confirmed by surgery or biopsy. These findings prompted a study of a patient with a suspected insulinoma where ultrasound, angiography and computed tomographic angiography had produced inconclusive results. On the first injection the subtracted images showed a filling defect in the region of the uncinate process about 1 cm across, as judged by the diameter of the endoscope, which is 13 mm. In view of the importance of precise location, a second injection was made and the findings confirmed. The tumour was removed at surgery and histological confirmation obtained. An attempt to demonstrate an insulinoma in a second case was unsuccessful as only the bile duct could be cannulated. In three cases (one of chronic pancreatitis, one unexplained abdominal pain and one suspected insulinoma) only a normal biliary tract could be shown. Of the remaining two cases, one showed dilated pancreatic and
DEMONSTRATION OF PANCREATIC PARENCHYMA BY DSA DURING ERCP
biliary ducts suggestive of an ampullary lesion and the other showed gall-stones in the common bile duct with a normal pancreatic duct. Serum amylase levels in six cases remained within our normal range (70-300 U/litre); 18 showed a brisk but transient hyperamylasaemia, maximum at 4 h and falling to normal within 2-3 days. Two patients developed clinical evidence of mild acute pancreatitis. DISCUSSION The use of DSA techniques in ERCP has been reported by Weiss and Gmelin (1983). One of the problems encountered was artefacts due to patient movement as the result of sedation preventing patient co-operation. We were able to overcome this problem by using the improved post-processing techniques now available and by taking at least two mask images prior to injection. These were invariably in a different phase of respiration and the one most appropriate to the rest of the run was used. Also, further masks to show the parenchyma of the gland can be made from the images where only the main duct is filled. Until the advent of non-ionic contrast media, demonstration of the pancreatic parenchyma during ERCP was avoided because of the risk of pancreatitis (Cotton, 1977). Yoshimoto et al. (1981) attempted to solve this problem by combining sodium and meglumine diatrizoate or sodium iothalamate with polyoxyethylene hydrogenated castor oil, a non-ionic surfactant, to increase parenchmyal staining without excessive injection pressure. They were able to show uniform smooth staining of the parenchyma in a normal gland, uneven staining and irregular contour in chronic pancreatitis and a parenchmyal filling defect in carcinoma. The increased sensitivity of DSA equipment, enabling it to detect a 1% difference in contrast, suggested that improved visualisation of the parenchyma would be achieved with a non-ionic medium alone, based on the method reported by Twomey et al. (1982). The study confirms that this is possible but that it may carry a higher risk. Acute pancreatitis is a recognised complication of ERCP (Cotton, 1977), occurring in about 1% of routine cases performed in our centre, a frequency similar to that found in other experienced units (Bilbao et al., 1976). Two patients in this study developed pancreatitis, an incidence of 7.3% which is comparable with early ERCP studies (Ruppin et al., 1974). One case, the patient with an insulinoma, had a mild episode lasting about 6 h with serum amylase reaching a peak of 6000
407
U/litre by 4 h and falling to normal within 48 h. This patient had two parenchymal injections, the decision to repeat the injection being taken after balancing the risk of complications against the need to confirm localisation. The second case occurred in a patient with unexplained abdominal pain who showed a normal pancreas. Again, the symptoms settled rapidly on conservative treatment, the amylase returning to normal in 72 h. It is worth noting that five of the six cases where the amylase remained within the normal range were in the parenchymal filling group. Against the increased risk of acute pancreatitis must be set the value of detecting small parenchymal lesions such as an insulinoma. Increasing experience with this technique may reduce the complication rate to that of the standard ERCP; monitoring the injection pressures required to produce parenchymal filling using the technique described by Kasugai et al. (1974) may prove helpful. In conclusion, digital imaging of the parenchyma of the pancreas during ERCP is feasible and can outline small parenchymal lesions as well as carcinoma and changes of chronic pancreatitis. However, using the techniques described in this study, we have found an increased risk of acute pancreatitis. Acknowledgements. We wish to acknowledge the Audio Visual Centre of the University of Newcastle upon Tyne for preparing the illustrations and Mrs K. J. Tunstall for typing the manuscript.
REFERENCES Bilbao, M. K., Dotter, C. T., Lee T. G & Katon, R. M. (1976). Complications of endoscopic retrograde cholangiopancreatography (ERCP). A study of 10,000 cases. Gastroenterology, 70, 314320. Cotton, P.B. (1977). Progress report. ERCP. Gut, 18, 316-341. Cotton, P. B. & Williams, C. B. (1983). Practical Gastrointestinal Endoscopy, pp. 62-68. Blackwell Scientific Publications, Oxford. Kasugai, T., Kuno, N. & Kizu, M. (1974). Manometric endoscopic retrograde pancreatocholangiography. American Journal of Digestive Diseases, 19, 485-501. Ruppin, H., Amon, R., Ett, W., Classen, M. & Demling, L. (1974). Acute pancreat~tis after endoscopic/radlologlcal pancreatography (ERP). Endoscopy, 6, 94-98. Twomey, B., Wilkins, R. A. & Levi, A. J. (1982). Pancreatic parenchymography using metrizamide (abstract). Gut, 23, 432. Weiss, H.-D. & Gmelin, E. (1983). Possibilities provided by digital subtraction angiography/digital subtraction radiography for improved visualization of the pancreas. Preliminary report. Contrast Media in Digital Radiography, Current Clinical Practice Series 12, pp. 343-345. Excerpta Medica, Amsterdam. Yoshimoto, S., Ohnishi, R., Dol, S. & Kawai, K. (1981). Endoscopic retrograde parenchymography. Radiology, 141,219-222.