Mark E. Bohlman

The role of magnetic resonance cholangiography in the management of patients with Gallstone pancreatitis

Objective:To examine the utility of magnetic resonance cholangiography (MRC) in the preoperative evaluation of patients with gallstone pancreatitis. Summary Background Data:Gallstone pancreatitis is often associated with the presence of common bile duct (CBD) stones that may require endoscopic removal prior to planned laparoscopic cholecystectomy. No reliable clinical criteria exist, however, that can accurately predict CBD stones and the need for preoperative endoscopic retrograde cholangiopancreatography (ERCP). Methods:Sixty-four patients were identified with gallstone pancreatitis based on clinical presentation and imaging studies over a three-and-a-half-year period. All patients underwent MRC, and the images were evaluated for gallstones, CBD stones, cholecystitis, and pancreatitis Results:Seventeen of the 64 patients (27%) with gallstone pancreatitis were found to have CBD stones confirmed by ERCP. MRC correctly predicted CBD stones in 16 of the 17 patients (sensitivity = 94%). In 1 additional patient, MRC demonstrated CBD stones not seen at ERCP, consistent with probable passage. By comparison, the sensitivities of other criteria for predicting CBD stones were (1) elevated bilirubin ≥2.0 mg/dL = 65%; (2) dilated duct on ultrasound = 55%; and (3) CBD stones on ultrasound = 27%. MRC was able to visualize gallbladder stones in 57 of 62 patients (94%) and correctly predicted acute cholecystitis in 6 of 8 patients. MRC also detected peripancreatic edema and inflammatory changes consistent with acute pancreatitis in 45 of 64 patients (70%). Conclusions:These results demonstrate that MRC can accurately identify CBD stones preoperatively in patients with gallstone pancreatitis and provide valuable information with respect to other biliary pathology, including cholelithiasis, acute cholecystitis, and pancreatitis. MRC is an effective noninvasive screening tool for CBD stones, appropriately selecting candidates for preoperative ERCP and sparing others the need for an endoscopic procedure with its associated complications.

The diagnostic utility of HASTE MRI in the evaluation of acute cholecystitis

PURPOSE The purpose of this study was twofold: (a) to determine the significance of high signal intensity surrounding the gallbladder as seen on T2-weighted HASTE (half-Fourier acquisition single shot turbo SE) MR images in patients with acute cholecystitis and (b) to determine the sensitivity of T2-weighted HASTE MR images in detecting gallbladder and common bile duct (CBD) calculi in patients with acute cholecystitis. METHOD Seventy-two patients with a suspicion of acute cholecystitis were referred for HASTE MRI over a 2 year period. Forty-one patients underwent MRI after sonography and the remaining 31 patients before sonography. MR images were independently evaluated for the presence of MR pericholecystic high signal and gallbladder and CBD calculi. Findings were correlated with results obtained at sonography and at surgery. RESULTS Of the 72 patients imaged with HASTE MRI, 55 had cholecystitis based on clinical, sonographic, and/or surgical findings. Of these, 45 had acute and 10 had chronic cholecystitis. HASTE MRI demonstrated MR pericholecystic high signal in 41 of 45 (91%) of the patients with acute cholecystitis. The sensitivity of HASTE MRI in diagnosing acute cholecystitis was 91%. The specificity was 79%. The positive predictive value was 87%, the negative predictive value was 85%, and the overall accuracy of the test was 89%. Gallbladder stones were seen by HASTE MRI in 38 of 41 (93%) of patients with acute calculus cholecystitis demonstrated at sonography. CBD stones were demonstrated by HASTE MRI in seven of nine (78%) patients and by sonography in five of nine (56%) patients with documented choledocholithiasis on conventional cholangiography. CONCLUSION HASTE MRI has a high degree of accuracy in diagnosing acute cholecystitis based on the single finding of pericholecystic MR high signal. A similar level of accuracy is demonstrated in detecting gallbladder stones. Biliary duct calculi are detected with even greater accuracy than with sonography in patients with acute cholecystitis. Invasive preoperative endoscopic retrograde cholangiography may therefore be limited to only those patients with acute cholecystitis and CBD stones demonstrated on HASTE MRI. These features make HASTE MRI and ideal imaging modality in the initial evaluation of acute biliary pain and may ultimately replace sonography in the preoperative evaluation of acute cholecystitis.

MR cholangiography in biliary obstruction using Half-Fourier acquisition

PURPOSE Our goal was to evaluate biliary obstruction using a T2-weighted, turbo, SE MR sequence with half-Fourier acquisition (HASTE). METHOD A prospective evaluation of 21 consecutive patients with clinical evidence of obstructive jaundice was carried out comparing HASTE MR cholangiography (MRC) to endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography. A control group of five normal volunteers was also evaluated. The study group was imaged with a 1.5 T MR scanner using a body coil. The HASTE sequence was applied in axial, coronal, and oblique sagittal planes. Ultrafast acquisition scanning times allowed the use of a single breath hold. Bile duct dilatation, level of obstruction, and cause of obstruction were assessed on both imaging modalities by two radiologists blinded to the clinical diagnosis and to each others results. RESULTS All studies were interpretable with anatomy well seen in 82% of the cases. MRCs of a normal control group were correctly interpreted. The presence of biliary dilatation was accurately depicted by HASTE MRC in 100% of patients with complete interobserver agreement. The level of obstruction was depicted correctly in 87% of patients with 93% interobserver agreement. The right main duct was seen by MRC in 80% of obstructed systems. The left main duct was seen in all obstructed patients. The gallbladder was identified in 88% of patients by MRC. Common bile duct stricture and stones could be differentiated as a cause of obstruction in all cases. CONCLUSION MRC using the HASTE imaging sequence can safely and accurately depict the presence and level of biliary obstruction. The fast acquisition time of 13 s/scan makes the technique suitable for uncooperative and ill patients. HASTE MRC should be considered an alternative procedure to direct cholangiography in selected patients.

COMPUTERIZED TOMOGRAPHY IN OBSTRUCTIVE SLEEP APNEA

Pathophysiologic changes during sleep in patients with obstructive apnea are often associated with alterations in upper airway function during awake periods. To determine whether these functional changes are related to abnormal airway structure, we performed computerized tomography (CT) in 20 awake patients with obstructive apnea and in 10 control subjects. The CT scan measurements of cross-sectional areas of the nasopharynx, oropharynx, and hypopharynx in apneic patients were significantly reduced (p < 0.05) compared with those in the control subjects. Sites of obstruction varied, and apparent airway occlusion occurred in 6 patients. Reduced pharyngeal size correlated with increased sleep-disordered breathing rates (p < 0.05), more severe nocturnal oxygen desaturation (p < 0.05), and the presence of a saw-tooth pattern of flow-volume curves obtained during awake periods (p < 0.05). Structural upper airway narrowing is detectable with CT in awake patients with obstructive sleep apnea.

Original PaperPerirenal MR high signal — A new and sensitive indicator of acute ureteric obstruction

PURPOSE This study was carried out to determine the incidence of perirenal magnetic resonance (MR) high signal in acute ureteric obstruction as demonstrated by half-Fourier acquisition single shot turbo spin-echo (HASTE) MR. In addition, we evaluated the sensitivity of this perirenal MR high signal as a predictor of acute ureteric obstruction. MATERIALS AND METHODS A prospective evaluation of 55 consecutive patients with suspected ureteric obstruction was carried out using the HASTE MR sequence. Images were compared to concurrent IV urography (IVU) or to computed tomography (CT) where these were available. Acute and chronic ureteric obstruction were differentiated by clinical evaluation. RESULTS Forty-one patients had obstructed kidneys. HASTE MR accurately predicted the presence of acute ureteric obstruction in 20/23 (87%) based on presence of perirenal MR high signal. None of these showed evidence of contrast medium extravasation on the concurrent i.v. urogram. 15/18 (83%) chronically obstructed kidneys demonstrated no perirenal high signal on HASTE MR, and the remaining three showed only a trace of perirenal high signal. CT showed perirenal stranding in only 2/8 patients with acutely obstructed kidneys. CONCLUSION In acute ureteric obstruction, HASTE MR shows perirenal high signal intensity much more commonly than IVU shows extravasation or CT showing perirenal stranding. The origin of this MR signal is uncertain but may represent oedema, lymphatic distension or free fluid from forniceal rupture. HASTE MR can accurately distinguish between acute and chronic ureteric obstruction based on the degree of perirenal high signal.

Perirenal MR high signal - A new and sensitive indicator of acute ureteric obstruction

PURPOSE This study was carried out to determine the incidence of perirenal magnetic resonance (MR) high signal in acute ureteric obstruction as demonstrated by half-Fourier acquisition single shot turbo spin-echo (HASTE) MR. In addition, we evaluated the sensitivity of this perirenal MR high signal as a predictor of acute ureteric obstruction. MATERIALS AND METHODS A prospective evaluation of 55 consecutive patients with suspected ureteric obstruction was carried out using the HASTE MR sequence. Images were compared to concurrent IV urography (IVU) or to computed tomography (CT) where these were available. Acute and chronic ureteric obstruction were differentiated by clinical evaluation. RESULTS Forty-one patients had obstructed kidneys. HASTE MR accurately predicted the presence of acute ureteric obstruction in 20/23 (87%) based on presence of perirenal MR high signal. None of these showed evidence of contrast medium extravasation on the concurrent i.v. urogram. 15/18 (83%) chronically obstructed kidneys demonstrated no perirenal high signal on HASTE MR, and the remaining three showed only a trace of perirenal high signal. CT showed perirenal stranding in only 2/8 patients with acutely obstructed kidneys. CONCLUSION In acute ureteric obstruction, HASTE MR shows perirenal high signal intensity much more commonly than IVU shows extravasation or CT showing perirenal stranding. The origin of this MR signal is uncertain but may represent oedema, lymphatic distension or free fluid from forniceal rupture. HASTE MR can accurately distinguish between acute and chronic ureteric obstruction based on the degree of perirenal high signal.

Rapid nephrostomy tube placement using a CT guided single stick system

ous iliac vein stents, 2/7 (28.5%) Wallstents and 5/7 (71.5%) wi th Palmaz stents. The etiologies included 5 multiple dialysis catheter placements, I venous obstruct ion secondary to prostrate carcinoma, and 1 Mays Thurner Syndrome. The location of the stentts were 2/7 (28.5%) right c o m m o n iliac vein, 2/7 (28.5%) left c o m m o n iliac vein, 2/7 (28.5%) right external iliac vein, and 1/7 (14.5%) left external iliac vein. Resul ts : All patients did well wi th no complications. One patient presented 8 mon ths later with a deep venous thrombosis due to iliac vein stenosis in a different location and needed the procedure repeated again. The patency of the iliac veins was evaluated by either contrast venography or ultrasound. Four patients had follow up studies for stent patency: 3 patients had contrast venography and I with ultrasound. Two patients were lost to follow up. Conclusions: Consideration of an iliac vein s tenoses should be made particularly in a patient wi th a history of multiple catheter placements . Iliac vein s tenoses can be treated safely wi th a percutaneous endovascular stent. Take H om e Points: See conclusions.