Gallbladder bile in cholecystitis: in vitro MR evaluation

Proton magnetic resonance spectroscopy as a potential tool for differentiating between abdominal fluid collections

PURPOSE

To determine the utility of proton magnetic resonance spectroscopy (MRS) in distinguishing abdominal fluid types.

MATERIALS AND METHODS

Abdominal fluid samples were obtained from patients undergoing therapeutic percutaneous drainage. In vitro spectroscopy was performed using a 1.5-T scanner and a head coil. Single voxel spectra were obtained using a point resolved spin-echo sequence with water suppression (TR/TE 2000 msec/35 msec). The peak pattern for each sample was examined and the signal-to-noise ratio (SNR) estimated (ratio of tallest peak to noise at <0 ppm).

RESULTS

Thirty-five samples were analyzed: purulent collection (eight), serosanguinous collection (eight), non-chylous ascites (six), chylous ascites (one), bile (seven), and bile with iodinated contrast media (five). The mean SNR of the dominant peak was: purulent collection, 12.7; serosanguinous collection, 3.2; non-chylous ascites, 2.4; chylous ascites, 8.8; bile, 1.4; and bile with contrast media, 60.8. Pus samples had a broad based peak pattern with continuous signal of >1.5 ppm width situated within the range 0.2-2.5 ppm, not found in other samples. Chylous ascites (one sample) had a distinctive peak at 1.2 ppm. Bile with contrast had three peaks at 3.5/3.6, 2.6, and 2.1 ppm. No other patterns were found to be discriminatory. Common non-specific patterns seen included a bifid peak at 1.1-1.3 ppm and a broad based peak situated between 3 and 4 ppm.

CONCLUSIONS

The H1 spectra of purulent fluid has a higher SNR than common non-purulent abdominal fluids and a distinct broad based peak pattern from 0.2-2.5 ppm. Proton spectroscopy may be a useful tool for distinguishing purulent from non-purulent intra-abdominal collections.

The interrupted rim sign in acute cholecystitis: a method to identify the gangrenous form with MRI

We present the imaging findings on MR of a patient with acute gangrenous cholecystitis that demonstrated patchy enhancement of the gallbladder mucosa on gadolinium-enhanced fat-saturated T1-weighted gradient echo images. This interrupted rim of mucosal enhancement correlated with patchy areas of necrosis and inflammation of the gallbladder mucosa on the histopathological examination.

On the appearance of bile in clinical MR cholangiopancreatography

PURPOSE

To study the appearance of bile in clinical MR cholangiopancreatography (MRCP) with special reference to its chemical and physical properties.

MATERIAL AND METHODS

Gallbladder bile was collected during surgery from 38 patients and studied with respect to chemical constituents. The relaxation rates 1/T1 and 1/T2 of bile were also determined in vitro. In 16 of these 38 patients, abdominal imaging was performed using MRCP as well as T1-weighted GE sequences.

RESULTS

For 9 of the 13 chemical parameters studied, a positive significant correlation with 1/T1 as well as 1/T2 was found. The median relaxation rates 1/T1 and 1/T2 were 0.76 and 1.48 s-1, respectively. The corresponding ranges were 0.38-3.13 s-1 and 0.70-5.75 s-1, respectively. On the MRCP images a few patients showed gallbladder of poor visibility due to low signal-to-noise ratio. This coincided with a high relaxation rate 1/T2 of bile. On the T1-weighted GE sequences a few patients showed hyperintense gallbladder relative to liver, coinciding with high relaxation rates 1/T1 of bile.

CONCLUSION

Bile was found to show a large interindividual variation with respect to relaxation rates 1/T1 and 1/T2. The relaxation rates increased with increasing amounts of substances in the bile. For some patients (11%) MRCP imaging is unsuccessful due to high relaxation rate of bile.

Value of magnetic resonance cholangiography in the preoperative diagnosis of common bile duct stones

OBJECTIVE

The aim of this study was to assess the performance of magnetic resonance cholangiography (MRC) in the preoperative diagnosis of choledocholithiasis.

METHODS

A total of 147 consecutive patients underwent MRC for clinical and biological signs of common bile duct stones. ERCP was then carried out in 101 patients in whom there was a past history of cholecystectomy. The remaining 46 patients without a past history of biliary surgery underwent cholecystectomy and intraoperative cholangiography (IOC). The diagnosis obtained by MRC was compared with the final diagnosis established after endoscopic or surgical removal of calculi.

RESULTS

A total of 113 patients had choledocholithiasis (single or multiple, including 15 cases of microlithiasis). There were no false-positive results with MRC. The false-negative results were caused mainly by small stones <3 mm in diameter, and to a lesser extent, cholangitis. Overall, the sensitivity was 93% and the specificity 100% for MRC in detecting common bile duct stones. The sensitivity and specificity of ERCP were respectively 94% and 100%, versus 93.5% and 93.3% for IOC. There was no statistically significant difference, however, between MRC and the other techniques.

CONCLUSION

MRC is a key technique in the preoperative diagnosis of choledocholithiasis. Its diagnostic value is comparable to ERCP, but it appears to be more specific than IOC. Nevertheless, its diagnostic capability remains limited in cases of microlithiasis and cholangitis.

A comparative study usefulness of magnetic resonance imaging in the diagnosis of acute cholecystitis

The utility of magnetic resonance imaging (MRI) in the diagnosis of acute cholecystitis was evaluated in 72 consecutive individuals (5 healthy, 13 with chronic cholecystitis and silent gallbladder stones, 43 without biliary or diffuse liver disease, and 11 with acute cholecystitis and gallbladder stones) with a 0.5-T superconducting unit. On the T1-weighted (500/20) and less T1-weighted axial spin-echo images (620/25), the liver/gallbladder signal intensity ratio (mean +/- SD) was 2.5 +/- 0.51 (n = 5) and 1.8 +/- 0.29 (n = 8) in acute cholecystitis; 0.9 +/- 0.42 (n = 6) and 1.0 +/- 0.29 (n = 9) in chronic cholecystitis; and 0.9 +/- 0.14 (n = 5) and 0.8 +/- 0.19 (n = 43) in normal gallbladder, respectively. Our results indicate that the liver/gallbladder signal intensity ratio on the T1-weighted image may be a simple and reliable indicator for the diagnosis of acute cholecystitis; we suggest further investigation to confirm these results.

High-field MRI of primary gallbladder carcinoma

The magnetic resonance (MR) imaging features are described in a case of gallbladder carcinoma presenting as a fungating mass associated with gallstones as well as biliary obstruction due to pancreaticoduodenal lymph node metastasis. The MR findings complemented diagnostic observations made on preoperative sonography and computed tomography of the abdomen.

Cholecystitis: diagnosis by MR imaging

Morphologic features which allow the diagnosis of acute cholecystitis by ultrasound and CT have now been observed by MR. When present, thickening of the gallbladder wall, intramural abscess, pericholecystic fluid, and the presence of gallstones may be more specific than MR characterization of gallbladder bile.

Determination of parameters effecting proton relaxation of hepatic and gallbladder biles in dogs

The parameters which are important in causing changes in the T1 and T2 proton magnetic relaxation times of dogs bile were investigated. Three factors were found to be important in causing relaxation in bile: (i) total bile salt concentration; (ii) total protein concentration, and (iii) viscosity. The T1 and T2 values of hepatic and gallbladder biles were found to be independent of specific gravity, osmolarity and electrolyte concentrations. In vitro experiments were conducted with taurocholic acid, bovine serum albumin and porcine stomach mucin to examine the effects of intermolecular interactions on proton relaxation. Relative to each of the molecules alone, various combinations of the bile salt and proteins exhibit relaxation rates of 20 to 60% below theoretically expected values. This influence of in vitro molecular interactions on T1 and T2 is also likely to occur in hepatic and gallbladder biles in vivo. Thus, the effects of complex intermolecular interactions associated with the gallbladder microenvironment complicate but likely will not preclude direct assessment of physiologic data with magnetic resonance imaging.