Superior diagnostic strength of combined contrast enhanced MR-angiography and MR-imaging compared to intra-arterial DSA in liver transplantation candidates

Diagnosis of Budd-Chiari syndrome: three-dimensional dynamic contrast enhanced magnetic resonance angiography

OBJECTIVE

To investigate the characteristics and diagnostic value of three-dimensional contrast-enhanced magnetic resonance angiography (3D CE-MRA) in the diagnosis of Budd-Chiari syndrome (BCS).

METHODS

One hundred thirty-three BCS patients underwent 3D CE-MRA, 64 patients had primary BCS, and 69 had secondary BCS.

RESULTS

Fifty five cases (41.4%) showed a segmental stenosis of the inferior vena cava, 9 cases (6.8%) a membranous obstruction of the inferior vena cava, 5 cases (3.8%) an unobstructed inferior vena cava and hepatic veno-occlusive condition, 16 cases (12.0%) an inferior vena cava stenosis and hepatic veno-occlusive disease, and 48 cases (36.1%) an intraluminal filling defect in the inferior vena cava. In 52 cases (39.1%), collateral blood vessels were formed, with deep, medium, and shallow portal veins and intrahepatic collateral veins in 88 groups. Among these, 41 (46.6%) had deep venous collateral channels, 24 (27.3%) had medium venous collateral channels, 9 (10.2%) had superficial venous collateral channels, 5 (5.7%) had portal vein collateral channels, and 9 (10.2%) had intrahepatic venous collateral channels.

CONCLUSION

3D CE-MRA is important in the clinical diagnosis and treatment planning of BCS and displays hepatic veins, the inferior vena cava system, and collateral vessels.

Hereditary Hemorrhagic Telangiectases

In hereditary hemorrhagic telangiectasia (HHT), the liver demonstrates a large pattern of findings, including telangiectases, arteriovenous shuntings, focal liver lesions, and ischemic cholangitis, and provides severe complications such as portal hypertension and cardiac failure. Magnetic resonance imaging allows obtaining complete information (parenchyma, biliary tract, and vessels) of the liver in a 1-step examination. Acknowledgment of typical magnetic resonance imaging features of liver involvement in hereditary hemorrhagic telangiectasia case will result in more accurate diagnosis and can guide therapeutic options.

Preoperative vascular imaging in pediatric liver transplantation

BACKGROUND/PURPOSE

There is a considerable variation in the use of vascular imaging techniques in the preoperative assessment of children scheduled for liver transplantation. Duplex Doppler ultrasound scan (US), magnetic resonance angiography (MRA), and conventional angiography are used to varying extents. The authors compared the results of preoperative vascular imaging studies with operative findings to determine their accuracy and usefulness.

METHODS

Results of preoperative vascular imaging in 37 consecutive children undergoing cadaveric liver transplantation were compared with operative findings. Those undergoing relatively elective transplantations were investigated by US and MRA (group 1), whereas those requiring urgent transplants were assessed only by US (group 2).

RESULTS

The median age of the cohort (15 boys; 22 girls) was 4 years (19 days to 16 years) and the median weight was 17 kg (2.9 to 82 kg). In group 1 (n = 26), 20 children had a normal-caliber, patent portal vein at transplant and 6 had a narrow but patent portal vein requiring venous reconstruction in 4. The sensitivity and specificity of MRA in the detection of an abnormally narrow portal vein were 100% (6/6) and 95% (19/20), respectively. If reversed or absent flow in the portal vein on US was taken as an indication of a potentially abnormal vein, the sensitivity and specificity of Doppler US were 83% (5/6) and 95% (19/20), respectively. Magnetic resonance angiography revealed arterial anomalies in 4 children but failed to detect small accessory hepatic arteries in 5. The single patient with an aberrant vena cava was identified by MRA. In group 2 (n = 11), venous findings at operation and on US were concordant in 10 (91%) cases; one infant with reversed flow in the portal vein on US had a thrombosed vein at surgery. Magnetic resonance angiography was useful in 2 patient groups: those with reversed flow on Doppler US or suspected portal vein thrombosis in whom an abnormal portal vein was present in 86% (6/7) and infants with the biliary atresia splenic malformation syndrome who had multiple venous and arterial anomalies.

CONCLUSIONS

A detailed Doppler examination of the hepatic vasculature by an experienced sonographer/radiologist provides sufficient vascular imaging for most children scheduled for cadaveric liver transplantation. Routine MRA is recommended in children with the biliary atresia splenic malformation syndrome and in those with abnormal duplex Doppler US findings. Although there are limited data in this study, MRA is also valuable in children with Budd-Chiari syndrome, liver tumors, or a previous portosystemic shunt.

Evaluation of Living Liver Transplant Donors: Method for Precise Anatomic Definition by Using a Dedicated Contrast-enhanced MR Imaging Protocol

Liver transplantation from a living donor involves removal of part of the donor liver in a fashion that does not endanger its vascular supply or metabolic function. The radiologist plays an important role in evaluation of the living donor to define the conditions under which graft donation is contraindicated and to identify anatomic variations that may alter the surgical approach. In the past, diagnostic work-up of the donor involved costly and invasive tests. Currently, dynamic contrast material-enhanced computed tomography and magnetic resonance (MR) imaging are the imaging tests performed, each of which has advantages and limitations. MR imaging performed with liver-specific and extravascular contrast agents may be used as a single imaging test for comprehensive noninvasive evaluation of living liver transplant donors. MR imaging provides valuable information about variations in the vascular and biliary anatomy and allows evaluation of the hepatic parenchyma for diffuse or focal abnormalities.

Preoperative evaluation of the entire hepatic vasculature in living liver donors with use of contrast-enhanced MR angiography and true fast imaging with steady-state precession

PURPOSE

To preoperatively assess the entire hepatic vasculature in living related liver donors with use of a combination of contrast material-enhanced magnetic resonance (MR) angiography and true fast imaging with steady-state precession (FISP).

MATERIALS AND METHODS

Twenty-five living potential liver donors were examined preoperatively on a 1.5T Siemens Sonata system. Twenty-four underwent surgery and two had catheter angiography performed to delineate complex anatomy. Contiguous 5-mm-thick, sub-second true FISP images of the liver were initially obtained during breath-holding in axial and coronal planes (repetition time [TR]/echo time [TE], 3.2/1.6; flip angle, 70 degrees ). MR angiography was performed with use of a three-dimensional (3D) gradient-echo fast low-angle shot (FLASH) pulse sequence (TR/TE, 3.0/1.2; flip angle, 25 degrees ), with 40 mL of Gadolinium DTPA injected at a rate of 2 mL/sec. One precontrast and two postcontrast coronal 3D volumes were acquired, each in a 20-second breath-hold, and two subtracted 3D sets were calculated. Arterial anatomy was assessed with use of maximum-intensity projection, volume rendering, and multiplanar reformatting algorithms. Hepatic and portal venous anatomy was evaluated with use of the true FISP images and the venous phase of the MR angiogram. Visualization of hepatic arterial branches was noted. Visualization of portal vein branches was scored on a scale of 0-5. The presence of anatomic variants was noted. Vascular anatomy was confirmed at the time of surgery and at catheter angiography.

RESULTS

Segmental branch vessels were visualized on MR angiography in the majority of cases. The segment four branch was identified in 96% patients. Variant arterial anatomy was seen in 50% of patients. MR angiography detected 10 of 11 arterial variants found at surgery and angiography. Visualization of portal vein branches was generally higher with true FISP compared to MR angiography. Twenty-four percent of patients had variant portal venous anatomy. Caudal hepatic veins were identified in 60% of patients, of which eight were significant (>5 mm). Hepatic and portal venous anatomy was accurately predicted by true FISP and MR angiography in all patients who went on to undergo surgery.

CONCLUSION

Preoperative imaging with use of a combination of contrast-enhanced MR angiography and true FISP provides a comprehensive assessment of the entire hepatic vasculature in living liver donors.