Gastrointestinal Imaging • Commentar y Takahashi and Chari MRCP Spin Labeling in Chronic Pancreatitis
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Gastrointestinal Imaging Commentary
MRI With Spin Labeling for Diagnosis of Early Chronic Pancreatitis Naoki Takahashi1 Suresh T. Chari2 Takahashi N, Chari ST
OBJECTIVE. The purpose of this article is to discuss MRI with spin labeling for diagnosis of chronic pancreatitis. CONCLUSION. Because of the unique functional information it can provide, MRI with spin labeling appears to be a useful adjunctive technique that can be added to routine anatomic imaging of the pancreas and pancreatic duct.
V
Keywords: chronic pancreatitis, main pancreatic duct, MRCP, pancreatic juice, spin labeling DOI:10.2214/AJR.14.12575 Received January 23, 2014; accepted without revision January 23, 2014. 1 Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Address correspondence to N. Takahashi ([email protected]). 2 Department of Medicine, Division of Gastroenterology, Mayo Clinic, Rochester, MN.
AJR 2014; 202:1035–1036 0361–803X/14/2025–1035 © American Roentgen Ray Society
isualization of pancreatic juice flow in the main pancreatic duct using unenhanced MRI with spin labeling was first described in healthy volunteers by two separate groups [1, 2]. In this issue of the AJR, the same two groups report that this technique can detect the age-related reduction of pancreatic juice flow in healthy volunteers and the reduction of flow in patients with chronic pancreatitis [3, 4]. Torigoe et al. [3] reported that the frequency of pancreatic juice flow observed and the velocity of pancreatic juice flow (secretion grade) both are negatively correlated with age in the healthy population. Sugita et al. [4] showed that the frequency of pancreatic juice flow observed and the velocity of pancreatic juice flow negatively correlate with the severity of chronic pancreatitis. MRI with spin labeling, originally developed for unenhanced MR angiography, is probably the first noninvasive imaging method that permits visualization and quantification of the pancreatic juice flow and is accomplished without any pharmacologic stress [5]. By selectively applying an inversion pulse and saturating the spins of the blood in the inflowing vessels, this technique causes the blood vessels in the area of interest to become bright. The technique has expanded its applications to include assessment of tissue perfusion, including tumor vascularity [6]. Recently, it has been applied in the assessment of flow in nonvascular structures, such as bile ducts [7] and the lymphatic system [8]. Will this new technique have diagnostic utility in diagnosis of early chronic pancre-
atitis? Patients with advanced chronic pancreatitis have the classic imaging triad of pancreatic atrophy, ductal dilation, and calcification. Such patients can be easily diagnosed without the aid of sophisticated testing. Apart from the typical features already noted, a few CT and MRI features of chronic pancreatitis have additionally been described, such as decreased T1 signal intensity, decreased contrast enhancement, and decreased apparent diffusion coefficient [9]. However, such features may be absent in patients with early chronic pancreatitis. The diagnosis of chronic pancreatitis is much harder to make in patients with pancreatic pain without typical radiologic features of chronic pancreatitis. In such patients, the diagnosis of early chronic pancreatitis is often based on endoscopic ultrasound, a procedure notorious for poor interobserver agreement on even seemingly straightforward findings such as small calcifications or presence of ductal strictures [10]. In addition, endoscopic ultrasound findings seen in early chronic pancreatitis are not specific for the disease. Advanced age, smoking, regular alcohol use, prior pancreatitis, and family history of pancreatic cancer are all associated with the presence of one or more features resembling chronic pancreatitis [11, 12]. Clearly, endoscopic ultrasound as currently performed is inadequate as a sole diagnostic modality for chronic pancreatitis. Therefore, attempts have been made to use other features of chronic pancreatitis, such as increased stiffness due to fibrosis (endoscopic ultrasound elastography) [13], decreased
AJR:202, May 2014 1035
Downloaded from www.ajronline.org by East Carolina University on 06/09/14 from IP address 150.216.68.200. Copyright ARRS. For personal use only; all rights reserved
Takahashi and Chari exocrine function (secretin-stimulated pancreatic bicarbonate concentration) [14], and decreased pancreatic juice volume (based on secretin MRI) [15–19], among others, to diagnose early chronic pancreatitis. Although the volume of pancreatic juice measured on secretin MRI has been shown to correlate with exocrine pancreatic function, it has not been shown useful for the diagnosis of early chronic pancreatitis. In fact, even in direct secretin- or cholecystokinin-stimulated pancreatic function tests, pancreatic juice volume has never been found to be a discriminating parameter for early chronic pancreatitis [14]; there was considerable overlap in pancreatic juice volumes in patients with and without chronic pancreatitis and only in advanced chronic pancreatitis was the volume consistently and appreciably decreased. Whether MRI with spin labeling will aid in the diagnosis of early chronic pancreatitis is unclear because it relies on the volume of pancreatic juice, similar to secretin MRI. A decrease in pancreatic juice flow may be due to early chronic pancreatitis, aging, or other unknown factors. Despite these challenges, however, the technique is noninvasive and appears to provide potentially useful functional information in quantifying pancreatic juice flow without pharmacologic stress. Other potential uses of this technique include evaluation of pancreatic outflow obstruction as a cause of recurrent acute pancreatitis, evaluation of pancreatic duct disconnection in necrotizing pancreatitis, and evaluation of reflux of pancreatic juice into the bile duct as a risk factor of cholangiocarcinoma [2], among others. Given the unique functional information it may provide, MRI with spin labeling appears to be a useful adjunctive technique that can easily be added to routine anatomic imaging of the pancreas and pancreatic duct.
References 1. Ito K, Torigoe T, Tamada T, Yoshida K, Murakami K, Yoshimura M. The secretory flow of pancreatic juice in the main pancreatic duct: visualization by means of MRCP with spatially selective inversionrecovery pulse. Radiology 2011; 261:582–586 2. Sugita R, Furuta A, Horaguchi J, et al. Visualization of pancreatic juice movement using unenhanced MR imaging with spin labeling: preliminary results in normal and pathophysiologic conditions. J Magn Reson Imaging 2012; 35:1119–1124 3. Torigoe T, Ito K, Yamamoto A, et al. Age-related change of the secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cinedynamic MRCP using spatially selective inversion recovery pulse. AJR 2014; 202:1022–1026 4. Sugita R, Furuta A, Yamazaki T, Itoh K, Fujita N, Takahashi S. Direct visualization of pancreatic juice flow using unenhanced MRI with spin labeling can be aid in diagnosing chronic pancreatitis. AJR 2014; 202:1027–1034 5. Miyazaki M, Lee VS. Nonenhanced MR angiography. Radiology 2008; 248:20–43 6. Lanzman RS, Robson PM, Sun MR, et al. Arterial spin-labeling MR imaging of renal masses: correlation with histopathologic findings. Radiology 2012; 265:799–808 7. Gonoi W, Akahane M, Watanabe Y, et al. Visualization of bile movement using MRI spin-labeling technique: preliminary results. AJR 2013; 201:133–141 8. Rane S, Donahue PM, Towse T, et al. Clinical feasibility of noninvasive visualization of lymphatic flow with principles of spin labeling MR imaging: implications for lymphedema assessment. Radiology 2013; 269:893–902 9. Akisik MF, Aisen AM, Sandrasegaran K, et al. Assessment of chronic pancreatitis: utility of diffusion-weighted MR imaging with secretin enhancement. Radiology 2009; 250:103–109 10. Wallace MB, Hawes RH, Durkalski V, et al. The reliability of EUS for the diagnosis of chronic pancreatitis: interobserver agreement among experienced endosonographers. Gastrointest En-
dosc 2001; 53:294–299 11. Yusoff IF, Sahai AV. A prospective, quantitative assessment of the effect of ethanol and other variables on the endosonographic appearance of the pancreas. Clin Gastroenterol Hepatol 2004; 2:405–409 12. Bhutani MS. Endoscopic ultrasonography: changes of chronic pancreatitis in asymptomatic and symptomatic alcoholic patients. J Ultrasound Med 1999; 18:455–462 13. Janssen J, Schlorer E, Greiner L. EUS elastography of the pancreas: feasibility and pattern description of the normal pancreas, chronic pancreatitis, and focal pancreatic lesions. Gastrointest Endosc 2007; 65:971–978 14. Lieb JG 2nd, Brensinger CM, Toskes PP. The significance of the volume of pancreatic juice measured at secretin stimulation testing: a single-center evaluation of 224 classical secretin stimulation tests. Pancreas 2012; 41:1073–1079 15. Matos C, Metens T, Deviere J, et al. Pancreatic duct: morphologic and functional evaluation with dynamic MR pancreatography after secretin stimulation. Radiology 1997; 203:435–441 16. Bali MA, Sztantics A, Metens T, et al. Quantification of pancreatic exocrine function with secretinenhanced magnetic resonance cholangiopancreatography: normal values and short-term effects of pancreatic duct drainage procedures in chronic pancreatitis—initial results. Eur Radiol 2005; 15:2110–2121 17. Cappeliez O, Delhaye M, Deviere J, et al. Chronic pancreatitis: evaluation of pancreatic exocrine function with MR pancreatography after secretin stimulation. Radiology 2000; 215:358–364 18. Manfredi R, Costamagna G, Brizi MG, et al. Pancreas divisum and “Santorinicele”: diagnosis with dynamic MR cholangiopancreatography with secretin stimulation. Radiology 2000; 217:403–408 19. Punwani S, Gillams AR, Lees WR. Non-invasive quantification of pancreatic exocrine function using secretin-stimulated MRCP. Eur Radiol 2003; 13:273–276
F O R YO U R I N F O R M AT I O N
The reader’s attention is directed to the articles pertaining to this commentary, which appear on the preceding pages.
1036
AJR:202, May 2014
Downloaded from www.ajronline.org by East Carolina University on 06/09/14 from IP address 150.216.68.200. Copyright ARRS. For personal use only; all rights reserved
Gastrointestinal Imaging Commentary
MRI With Spin Labeling for Diagnosis of Early Chronic Pancreatitis Naoki Takahashi1 Suresh T. Chari2 Takahashi N, Chari ST
OBJECTIVE. The purpose of this article is to discuss MRI with spin labeling for diagnosis of chronic pancreatitis. CONCLUSION. Because of the unique functional information it can provide, MRI with spin labeling appears to be a useful adjunctive technique that can be added to routine anatomic imaging of the pancreas and pancreatic duct.
V
Keywords: chronic pancreatitis, main pancreatic duct, MRCP, pancreatic juice, spin labeling DOI:10.2214/AJR.14.12575 Received January 23, 2014; accepted without revision January 23, 2014. 1 Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Address correspondence to N. Takahashi ([email protected]). 2 Department of Medicine, Division of Gastroenterology, Mayo Clinic, Rochester, MN.
AJR 2014; 202:1035–1036 0361–803X/14/2025–1035 © American Roentgen Ray Society
isualization of pancreatic juice flow in the main pancreatic duct using unenhanced MRI with spin labeling was first described in healthy volunteers by two separate groups [1, 2]. In this issue of the AJR, the same two groups report that this technique can detect the age-related reduction of pancreatic juice flow in healthy volunteers and the reduction of flow in patients with chronic pancreatitis [3, 4]. Torigoe et al. [3] reported that the frequency of pancreatic juice flow observed and the velocity of pancreatic juice flow (secretion grade) both are negatively correlated with age in the healthy population. Sugita et al. [4] showed that the frequency of pancreatic juice flow observed and the velocity of pancreatic juice flow negatively correlate with the severity of chronic pancreatitis. MRI with spin labeling, originally developed for unenhanced MR angiography, is probably the first noninvasive imaging method that permits visualization and quantification of the pancreatic juice flow and is accomplished without any pharmacologic stress [5]. By selectively applying an inversion pulse and saturating the spins of the blood in the inflowing vessels, this technique causes the blood vessels in the area of interest to become bright. The technique has expanded its applications to include assessment of tissue perfusion, including tumor vascularity [6]. Recently, it has been applied in the assessment of flow in nonvascular structures, such as bile ducts [7] and the lymphatic system [8]. Will this new technique have diagnostic utility in diagnosis of early chronic pancre-
atitis? Patients with advanced chronic pancreatitis have the classic imaging triad of pancreatic atrophy, ductal dilation, and calcification. Such patients can be easily diagnosed without the aid of sophisticated testing. Apart from the typical features already noted, a few CT and MRI features of chronic pancreatitis have additionally been described, such as decreased T1 signal intensity, decreased contrast enhancement, and decreased apparent diffusion coefficient [9]. However, such features may be absent in patients with early chronic pancreatitis. The diagnosis of chronic pancreatitis is much harder to make in patients with pancreatic pain without typical radiologic features of chronic pancreatitis. In such patients, the diagnosis of early chronic pancreatitis is often based on endoscopic ultrasound, a procedure notorious for poor interobserver agreement on even seemingly straightforward findings such as small calcifications or presence of ductal strictures [10]. In addition, endoscopic ultrasound findings seen in early chronic pancreatitis are not specific for the disease. Advanced age, smoking, regular alcohol use, prior pancreatitis, and family history of pancreatic cancer are all associated with the presence of one or more features resembling chronic pancreatitis [11, 12]. Clearly, endoscopic ultrasound as currently performed is inadequate as a sole diagnostic modality for chronic pancreatitis. Therefore, attempts have been made to use other features of chronic pancreatitis, such as increased stiffness due to fibrosis (endoscopic ultrasound elastography) [13], decreased
AJR:202, May 2014 1035
Downloaded from www.ajronline.org by East Carolina University on 06/09/14 from IP address 150.216.68.200. Copyright ARRS. For personal use only; all rights reserved
Takahashi and Chari exocrine function (secretin-stimulated pancreatic bicarbonate concentration) [14], and decreased pancreatic juice volume (based on secretin MRI) [15–19], among others, to diagnose early chronic pancreatitis. Although the volume of pancreatic juice measured on secretin MRI has been shown to correlate with exocrine pancreatic function, it has not been shown useful for the diagnosis of early chronic pancreatitis. In fact, even in direct secretin- or cholecystokinin-stimulated pancreatic function tests, pancreatic juice volume has never been found to be a discriminating parameter for early chronic pancreatitis [14]; there was considerable overlap in pancreatic juice volumes in patients with and without chronic pancreatitis and only in advanced chronic pancreatitis was the volume consistently and appreciably decreased. Whether MRI with spin labeling will aid in the diagnosis of early chronic pancreatitis is unclear because it relies on the volume of pancreatic juice, similar to secretin MRI. A decrease in pancreatic juice flow may be due to early chronic pancreatitis, aging, or other unknown factors. Despite these challenges, however, the technique is noninvasive and appears to provide potentially useful functional information in quantifying pancreatic juice flow without pharmacologic stress. Other potential uses of this technique include evaluation of pancreatic outflow obstruction as a cause of recurrent acute pancreatitis, evaluation of pancreatic duct disconnection in necrotizing pancreatitis, and evaluation of reflux of pancreatic juice into the bile duct as a risk factor of cholangiocarcinoma [2], among others. Given the unique functional information it may provide, MRI with spin labeling appears to be a useful adjunctive technique that can easily be added to routine anatomic imaging of the pancreas and pancreatic duct.
References 1. Ito K, Torigoe T, Tamada T, Yoshida K, Murakami K, Yoshimura M. The secretory flow of pancreatic juice in the main pancreatic duct: visualization by means of MRCP with spatially selective inversionrecovery pulse. Radiology 2011; 261:582–586 2. Sugita R, Furuta A, Horaguchi J, et al. Visualization of pancreatic juice movement using unenhanced MR imaging with spin labeling: preliminary results in normal and pathophysiologic conditions. J Magn Reson Imaging 2012; 35:1119–1124 3. Torigoe T, Ito K, Yamamoto A, et al. Age-related change of the secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cinedynamic MRCP using spatially selective inversion recovery pulse. AJR 2014; 202:1022–1026 4. Sugita R, Furuta A, Yamazaki T, Itoh K, Fujita N, Takahashi S. Direct visualization of pancreatic juice flow using unenhanced MRI with spin labeling can be aid in diagnosing chronic pancreatitis. AJR 2014; 202:1027–1034 5. Miyazaki M, Lee VS. Nonenhanced MR angiography. Radiology 2008; 248:20–43 6. Lanzman RS, Robson PM, Sun MR, et al. Arterial spin-labeling MR imaging of renal masses: correlation with histopathologic findings. Radiology 2012; 265:799–808 7. Gonoi W, Akahane M, Watanabe Y, et al. Visualization of bile movement using MRI spin-labeling technique: preliminary results. AJR 2013; 201:133–141 8. Rane S, Donahue PM, Towse T, et al. Clinical feasibility of noninvasive visualization of lymphatic flow with principles of spin labeling MR imaging: implications for lymphedema assessment. Radiology 2013; 269:893–902 9. Akisik MF, Aisen AM, Sandrasegaran K, et al. Assessment of chronic pancreatitis: utility of diffusion-weighted MR imaging with secretin enhancement. Radiology 2009; 250:103–109 10. Wallace MB, Hawes RH, Durkalski V, et al. The reliability of EUS for the diagnosis of chronic pancreatitis: interobserver agreement among experienced endosonographers. Gastrointest En-
dosc 2001; 53:294–299 11. Yusoff IF, Sahai AV. A prospective, quantitative assessment of the effect of ethanol and other variables on the endosonographic appearance of the pancreas. Clin Gastroenterol Hepatol 2004; 2:405–409 12. Bhutani MS. Endoscopic ultrasonography: changes of chronic pancreatitis in asymptomatic and symptomatic alcoholic patients. J Ultrasound Med 1999; 18:455–462 13. Janssen J, Schlorer E, Greiner L. EUS elastography of the pancreas: feasibility and pattern description of the normal pancreas, chronic pancreatitis, and focal pancreatic lesions. Gastrointest Endosc 2007; 65:971–978 14. Lieb JG 2nd, Brensinger CM, Toskes PP. The significance of the volume of pancreatic juice measured at secretin stimulation testing: a single-center evaluation of 224 classical secretin stimulation tests. Pancreas 2012; 41:1073–1079 15. Matos C, Metens T, Deviere J, et al. Pancreatic duct: morphologic and functional evaluation with dynamic MR pancreatography after secretin stimulation. Radiology 1997; 203:435–441 16. Bali MA, Sztantics A, Metens T, et al. Quantification of pancreatic exocrine function with secretinenhanced magnetic resonance cholangiopancreatography: normal values and short-term effects of pancreatic duct drainage procedures in chronic pancreatitis—initial results. Eur Radiol 2005; 15:2110–2121 17. Cappeliez O, Delhaye M, Deviere J, et al. Chronic pancreatitis: evaluation of pancreatic exocrine function with MR pancreatography after secretin stimulation. Radiology 2000; 215:358–364 18. Manfredi R, Costamagna G, Brizi MG, et al. Pancreas divisum and “Santorinicele”: diagnosis with dynamic MR cholangiopancreatography with secretin stimulation. Radiology 2000; 217:403–408 19. Punwani S, Gillams AR, Lees WR. Non-invasive quantification of pancreatic exocrine function using secretin-stimulated MRCP. Eur Radiol 2003; 13:273–276
F O R YO U R I N F O R M AT I O N
The reader’s attention is directed to the articles pertaining to this commentary, which appear on the preceding pages.
1036
AJR:202, May 2014
