avone P

Magnetic resonance-cholangiopancreatography in the diagnosis of biliopancreatic diseases

BACKGROUND Magnetic resonance cholangiopancreatography (MRCP) is a new, noninvasive imaging technique for the visualization of the biliary ducts with cholangiographic images similar to those obtained with endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography. No contrast medium injection is used. The aim of this study was to assess the feasibility of MRCP versus ERCP in the diagnosis of biliary tract and pancreatic diseases. PATIENTS AND METHODS One hundred and thirty-six patients were submitted to MRCP. They were referred to MR study according to four inclusion criteria: (1) evidence or suspicion of choledocholithiasis, (2) benign or malignant bile ducts stenosis, (3) follow-up of patients submitted to biliary-enteric anastomosis, and (4) chronic pancreatitis with Wirsung duct dilatation. The MRCP was performed with a 0.5T superconducting magnet (Philips Gyroscan T5). When neoplastic disease was detected, additional images on axial planes were acquired. MRCP allowed images of diagnostic value to be obtained in all the cases. RESULTS In choledocholithiasis, MRCP showed 91.6% sensitivity, 100% specificity, and overall diagnostic accuracy 96.8%. Of 48 patients with stenotic lesions, 16 were correctly characterized as benign and 30 as malignant. Two cases of focal chronic pancreatitis were misdiagnosed as pancreatic head carcinoma. In the patients submitted to biliary-enteric anastomosis, MCRP was able to detect the dilatation of the intrahepatic ducts, the stenosis, and associated stones in all 8 positive cases. In the remaining 7 patients with mild signs of cholangitis, MCRP showed irregular aspects of the biliary tree in the main ducts. In the 11 patients with chronic pancreatitis, MCRP was able to depict the dilated Wirsung duct and the stenotic tract, although the fine details of the secondary ducts were not evaluated due to the low spatial resolution as compared with conventional films. CONCLUSIONS MRCP can be considered a technique able to completely replace diagnostic ERCP. Further studies are necessary for a better evaluation of the potential advantages and disadvantages of this technique.

Pancreatic adenocarcinoma: combination of MR imaging, MR angiography and MR cholangiopancreatography for the diagnosis and assessment of resectability

Abstract. The purpose of this study was to determine the possibility of integrating MR cholangiopancreatography (MRCP) and MR angiography (MRA) to conventional MR images in the diagnosis and assessment of resectability of pancreatic adenocarcinoma. Twenty-three patients with pancreatic adenocarcinoma were prospectively examined with MR. Conventional MR images were acquired in all patients. Three-dimensional MRCP and MRA images were acquired in all patients with suspected biliary and vascular involvement. Acquisition time was less than 45 min in all cases. Images were independently evaluated by two radiologists, with final reading decided by consensus among readers. Diagnosis was confirmed with surgery in 16 patients and with percutaneous biopsy in 7. Concordance among readers was high with a kappa value of 0.83. Pancreatic adenocarcinoma was observed in all patients. Correct assessment of unresectability due to vascular involvement was found in 22 of 23 patients. Biliary obstruction was evident in 13 patients, involving the biliary and pancreatic ducts in 9 and the biliary ducts only in 4. Technical advances permit extensive use of MRI in the evaluation of abdominal pathologies. The combination of MR imaging, MRCP, and MRA can provide sufficient information for the diagnosis and assessment of resectability of pancreatic adenocarcinoma, which otherwise would require three different exams.

Pancreatic β-cell tumors : MRI

Ten consecutive patients with surgically proven β-islet cell tumors, strongly suspected clinically because of positive laboratory findings, were studied by MRI at 0.5 T. Results were correlated with CT and angiography. MRI detected all 10 insulinomas, with the location confirmed at surgery. Lesion size was > 1 cm in three cases, between 1 and 2 cm in five cases, and between 2 and 3 cm in two cases. A false-negative diagnosis was obtained with CT in 6 of 10 and with angiography in 3 of 10 cases. Our results suggest that if motion artifact can be controlled or reduced, MRI can be employed to localize insulinomas in patients with positive clinical and laboratory findings.

MRI of the biliary and pancreatic ducts

Abstract. Magnetic resonance Cholangiopancreatography (MRCP) is a non-invasive imaging technique able to provide projectional images of the bile ducts. Different sequences, using both breath-hold and non-breath-hold acquisition techniques, have been employed in order to obtain MRCP images. The authors discuss technical aspects, considering both three-dimensional non-breath-hold techniques and two-dimensional breath-hold, multi-slice and thick slab sequences. Clinical applications of MRCP are evaluated, presenting data from both the literature and personal experience. The main indication for MRCP study is represented by the evaluation of common bile duct obstruction, with the aim of assessing the presence of the obstruction (accuracy 85–100 %) and, subsequently, its level (accuracy 91–100 %) and its cause. The utility of associating conventional MR images to MRCP in malignant strictures, in order to characterize and stage the malignant lesion, is also discussed. Finally, data are presented regarding the indications and the utility of MR-pancreatography in the evaluation of patients with pancreatic duct anomalies and chronic pancreatitis.

Role of MR venography in the evaluation of deep venous thrombosis

Purpose: MR venography has been recommended for the evaluation of deep venous thrombosis. The purpose of our study was to determine the role of MR venography, in particular at the level of the pelvis where other diagnostic modalities show major limitations. Materials and Methods: Forty-three patients with clinical suspicion of deep venous thrombosis were examined by means of pelvic MR venography. In all cases, a 2D-TOF sequence was used with cranial arterial presaturation. In selected cases, i.e. when a small intraluminal filling defect was present, a cine-PC sequence was used in addition in order to exclude the presence of a pulsatility artifact as causing the filling defect. In all cases, contrast venography was also performed and considered to be the standard of reference. Results: MR venography showed 26 patients to be positive for deep venous thrombosis at the pelvic level. These positive results were correct in 25 cases. The analysis of the results provided values of sensitivity and specificity of respectively 100% and 94%, with an overall accuracy of 97.6%. Conclusion: Our results indicate that MR can provide highly accurate images, similar to those of contrast venography, in a noninvasive fashion. It is particularly useful in the pelvic region where the limitations of other imaging modalities are more evident.

MR cholangiography (MRC) in the evaluation of CBD stones before laparoscopic cholecystectomy

AbstractBackground: The aim of our work was to evaluate the predictive value of MR cholangiography (MRC) in detecting CBD stones before laparoscopic surgical treatment. Methods: MRC was performed as a unique preoperative imaging modality in 45 selected patients (16 male; 29 female; age range: 28–72; mean age: 54.4) before laparoscopic cholecystectomy. MRC imaging was obtained with a 3D Turbo Spin-Echo sequence (TR = 3000 ms, TE = 700 ms, Echo Train Length—128) with an acquisition time of 5 min 48 s. Diagnostic confirmation was obtained in all the cases at i.o. cholangiography. When a stone was detected it was removed by transcystic or transcholedochal approach. Results: Eighteen of the 45 patients (40%) had CBD stones. MRC correctly evaluated 16 out of 18 stones, with a resulting sensitivity of 88.9%, specificity 100%, positive predictive value 100%, negative predictive value 90%, and accuracy 95.6%. Conclusions: Despite the good results of MRC, it cannot be proposed as a screening technique to be performed in all patients submitted to laparoscopic cholecystectomy due to high cost and the limited amount of MR equipment. In conclusion, only selected patients should be submitted to MRC before laparoscopic cholecystectomy.

Localization of pancreatic insulinomas with MR imaging at 0.5 T.

Objective: To determine the role of MR imaging in the localization of pancreatic insulinomas in patients with clinical and laboratory diagnosis of insulinproducing tumor. Material and Methods: Thirty-one patients presenting with signs and symptoms of pancreatic insulinomas were prospectively included in our study. Twenty-six patients underwent surgery, and pathologic specimens were examined: 5 patients, in whom the initial diagnosis of insulinoma was excluded, were also studied and then followed up. All patients were studied with a high gradient power 0.5 T magnet. Images were evaluated by 2 radiologists blinded to previous investigations, tests and results. Results: MR imaging correctly localized 24 of the 26 insulinomas (2 were false-negative and 1 false-positive) and was correctly negative in the 5 control patients. the interobserver agreement had a kappa value of 0.89. Conclusion: MR imaging was accurate in localizing pancreatic insulinomas and as a consequence, patients in our institution are now submitted to surgery directly after the MR examination. Invasive methods are considered only in cases in which, despite clear biochemical results, MR imaging has not demonstrated a pancreatic focal lesion.

MR cholangiography: techniques and clinical applications

Abstract. Magnetic resonance cholangiography (MRCP) is a new non-invasive imaging technique for the evaluation of bilio-pancreatic disorders. Different sequences, using both breathhold and non-breathhold techniques, have been employed in order to obtain MRCP images. The authors discuss the technical aspects, particularly focusing their attention on a non-breathhold, three-dimensional, fat-suppressed turbo-spin-echo sequence, optimized on a 0.5-T magnet with 15 mT/m gradients. Clinical applications of MRCP are evaluated, presenting data from both the literature and personal experience. The main indication for MRCP study is represented by the evaluation of common bile duct obstruction, with the aim of assessing the presence of the obstruction (accuracy 85–100 %) and, subsequently, its level (accuracy 91–100 %) and its cause. The utility of associating conventional MR images to MRCP in malignant strictures in order to characterize and stage the malignant lesions is also discussed. Finally, data are presented regarding the indications and utility of MR pancreatography in the evaluation of patients with chronic pancreatitis.

MR pyelography and conventional MR imaging in urinary tract obstruction

Purpose: To evaluate the possible role of MR imaging in the assessment of patients with urinary tract obstruction by combining conventional MR imaging and MR pyelography (MRP). Material and Methods: Forty-three patients with dilated upper urinary tract were studied with a high gradient strength 0.5 T magnet. Respiratory compensated T1-weighted, SE and T2-weighted TSE sequences were acquired in all patients. MRP images were obtained by using a respiratory compensated 3D T2-weighted TSE sequence. MRP images were reconstructed with a MIP algorithm. In all cases, urography and/or ascending pyelography were also performed. Images were independently evaluated by two radiologists. Results: The dilated tract ureter and the level of the obstruction could be correctly demonstrated in all cases. The cause of the obstruction was correctly demonstrated by examiner 1 in 90% and by examiner 2 in 88%. The interobserver agreement was high with a kappa-value of 0.96. Conclusion: In cases of obstructive hydroureteronephrosis MR imaging, combining MRP and conventional sequences, can be proposed as an accurate technique in the assessment of level and cause of obstruction.

MR cholangiopancreatography (MRCP) at 0.5 T: technique optimisation and preliminary results

The aim of our study was to evaluate the feasibility of MR cholangiopancreatography (MRCP) at 0.5 T. To our knowledge no previous studies of MRCP have been performed at mid-field strength. Thirty-one patients with dilated biliary systems were examined with three-dimensional MRCP. All patients were studied with a 0.5 T superconducting magnet. A three-dimensional turbo spin-echo (TSE) sequence was acquired (TR = 3000 ms, TE = 700 ms, echo train length = 45; acquisition time = 14 min 10 s). Coronal images were post-processed with the MIP algorithm. Recently, the parameters have been optimised (TR = 3000 ms, TE = 700 ms, echo train length =128), reducing the acquisition time to 3 min. Endoscopic retrograde cholangiopancreatography (ERCP) was performed in 26 cases; 5 patients underwent percutaneous transhepatic cholangiography PTC. MRCP and ERCP images were evaluated by an experienced radiologist and an endoscopist. MRCP of diagnostic quality was acquired in all patients. Choledocholithiasis was correctly evaluated by MRCP in 12 of 12 patients, compared with 11 correct diagnoses by ERCP. The presence and the level of the stricture were accurately shown in 16 of 16 patients with MRCP and in 13 of 16 patients with ERCP. The peripheral biliary tree above the obstruction and pancreatic duct were better evaluated by MRCP in all cases. In 3 of 3 patients who had undergone bilio-enteric surgery, a correct evaluation of the site of the anastomosis was possible with MRCP. It is concluded that MRCP performed at mid-field strength allows good visualisation of the dilated biliary system. Excellent results have been obtained on comparison with ERCP. MRCP performed at mid-field strength could have the same clinical value as high field strength MRCP.