The Accuracy of Contrast Abdominal CT for the Detection of High-Grade Esophageal and Gastric Varices in Patients With Cirrhosis

Study Group -We screened a population of 581 consecutive patients with cirrhosis who were scheduled to undergo upper gastrointestinal endoscopy. Exclusion criteria included inability to provide consent, patients who had previously undergone liver transplantation, previous portosystemic shunt procedure, or had a recent history (< 7 days) of upper gastrointestinal bleeding . In addition, patients with renal insufficiency defined as a serum creatinine of > 1.7 mg/dL in non-diabetics or >1.5 mg/dL in diabetics were excluded given concerns regarding the requirement of intravenous contrast during CT. Approximately 300 patients met inclusion criteria for screening for esophageal varices. Patients who had endoscopic variceal therapy (n=19) were also screened and 10 patients were included in the study to determine the role of CT imaging in determining the presence of varices in this group of patients. The last endoscopic therapy session in this group was greater than four weeks prior to the CT scan in order to eliminate any potential radiological artifact from the endoscopic treatment. Patients who met inclusion criteria (n=300) but declined entry into the study cited either scheduling conflicts (n=142),or fear of radiation (n=24) . The diagnosis of cirrhosis in the 134 patients who consented to the study was based on histology (N = 76); or the presence of ascites, thrombocytopenia or splenomegaly combined with low serum albumin (<3.4 g/dL) and prolongation of the prothrombin time (INR > 1.3) with compatible abdominal imaging (N = 58). No endoscopies were performed purely for research purposes. Written informed consent was obtained from all patients who were enrolled into the study. Of the 134 patients who consented, 102 completed both endoscopic and CT examinations.

To reflect practice in the real world, the endoscopic procedures were deliberately chosen to be carried out by regularly scheduled endoscopists rather than a small selected group of very experienced endoscopists. Varices were regarded as present or absent, with size recorded as either large (≥5 mm diameter) or small (<5 mm diameter) based on subjective assessment of diameter.. Titrated sedation was undertaken in all patients with midazolam and fentanyl.. The size of the esophageal varices was measured in the distal 5 cm of the esophagus during withdrawal of the instrument.

Two gastrointestinal radiologists (R1 and R2), each with over 10 years of experience and blinded to each other's evaluation, as well as to the results of the endoscopy, read each CT study. Axial images were evaluated to determine the presence and size of esophageal and gastric varices.

Multidetector CT scans (four detectors or higher)were performed using 0.5 second rotation time ,scanner settings of 250 mAs and 120 kVp, slice thickness 3 mm, and 3 mm reconstruction interval. Intravenous low osmolar iodinated contrast (Omnipaque 300; GE Healthcare) was administrated at a rate of 4ml/second, with late arterial phase scanning initiated 35 seconds after contrast injection, and carried out from the liver dome through the liver and pancreas. Portal phase imaging was initiated 70 seconds after contrast injection, and was carried out from above the diaphragm to the iliac crest. Partial phase images were also reconstructed to a nominal slice thickness of 0.75-1.5 mm and a 20cm field of view to maximize spatial resolution.. The total effective radiation dose for this protocol was 15mSv. There was a possible clinical indication to perform CT of the abdomen in 44 of the patients; CT was performed solely for research purposes in 58 patients. Large esophageal varices on CT scan were defined as those that were measured as greater than or equal to 5 mm in diameter, with small varices being those that measured less than 5 mm in diameter.

To determine degree of interobserver variability regarding characterization of variceal size between endoscopists, photographs of esophageal varices were taken during endoscopies and randomly selected images were circulated among 5 endoscopists, 2 with <5 years' experience in practice and 3 with >15 years' experience. The endoscopists were blinded to the results of the other's interpretation and were asked to characterize the endoscopic images as either small,large, or absent varices.