CT in hepatic cirrhosis and chronic hepatitis.

Cirrhosis is a diffuse liver disease with premalignant potential in which hepatocellular carcinoma (HCC) frequently develops. The hemodynamics of contrast material are the key to diagnosis of focal liver lesions with computed tomography (CT). Lesions with arterial-dominant vascularity, such as HCC, show brisk enhancement during the arterial phase, whereas lesions with portal blood supply can appear as hyperenhancing lesions in the portal phase. The advent of helical CT has significantly improved the CT examination of the liver because the arterial phase can be displayed independently of the portal phase. The addition of arterial phase imaging to conventional portal phase imaging seems to improve tumor detection and characterization. Although HCC is the single most frequent tumor seen in chronic liver disease, other lesions such as peripheral cholangiocarcinoma and hemangioma should be considered in the differential diagnosis. Optimization of helical CT techniques may allow better detection and characterization of these lesions. In addition to tumor detection, CT plays an important role in preoperative staging of HCC as well as in preoperative assessment of patient candidates to hepatic transplantation. The use of CT angiography with maximum intensity projection techniques may allow for better preoperative work-up and vascular mapping in HCC patients. This article shows the spectrum of helical CT findings in chronic liver disease and specifically in the imaging of HCC and other focal lesions.

PET/CT fusion scan in lung cancer: current recommendations and innovations.

Combined fluorodeoxyglucose-positron emission tomography (PET)/ computed tomography (CT) imaging has the potential to become the new standard imaging modality for the staging and restaging of patients with lung cancer. PET/CT is superior to PET alone, CT alone, and visual correlation of both techniques separately. In particular, it improves T3 and T4 staging and delineation of tumors associated with atelectasis. CT contrast media enhancement is probably only still needed when a substantial mediastinal tumor component is present and delineation of tumor from vascular structures is relevant. PET/CT is very accurate in detecting mediastinal nodal disease, but false-positive results are sufficiently frequent to require sampling in some positive cases. Whole-body PET/CT is the most sensitive technique for detecting extracranial metastatic disease, unexpected additional primary malignancies, and recurrence. Innovations include therapy monitoring, prognostic information, evaluation of small-cell lung cancer, its use for radiotherapy planning, and four-dimensional respiratory gating acquisition.

Biliary complications after liver transplantation: diagnosis with MR cholangiopancreatography.

OBJECTIVE: We sought to evaluate MR cholangiopancreatography (MRCP) as the only imaging procedure used in the diagnosis and management of biliary complications after orthotopic liver transplantation (OLT). CONCLUSION: MRCP is a useful imaging procedure in the assessment of biliary complications after OLT.

Selective use of low-osmolality contrast media in computed tomography.

The aim of this study was to describe our experience and institutional savings with a selective use of low-osmolality contrast media (LOCM) in CT. From 1995 to 1998, a total of 19,834 contrast-enhanced CT examinations were performed at our institution. Contrast was injected with a power injector and large venous catheter, 20-G for 2- to 3-ml rate and 18-G for 3- to 5-ml rate. High-osmolality contrast media was used in 13,670 patients (71%). The LOCM was used in 5884 (29%) patients. Our guidelines for the use of LOCM included cardiac dysfunction, severe pulmonary impairment, history of allergy or prior moderate reaction to HOCM and severe debilitation. Prior to the injection of HOCM, 10 mg of metoclopramide (Primperan, Delagrange Quétigny, France) were administered to reduce nausea and vomiting. In the HOCM group there were 304 minor or mild adverse reactions (2.2%), and 10 severe adverse reactions (0.08%). In the LOCM there were 34 mild or moderate adverse reactions (0.59%) and 3 severe adverse reactions (0.05%). Significant differences in terms of mild adverse reactions were found between HOCM and LOCM (Fischer's test, p<0.001). No significant differences were found in terms of severe adverse reactions ( p=0.27). After subtracting the cost of treating additional adverse reactions, the net differential cost between universal and selective use of LOCM was 565,285 Euro (601,067 US dollars). This means a net increase of 41.4 Euro per patient or 414,000 Euro per 10,000 patients (438,840 US dollars). Selective use of LOCM in CT is safe and effective and results in a substantial reduction in costs.

Pretransplantation diagnosis and staging of hepatocellular carcinoma in patients with cirrhosis: value of dual-phase helical CT.

OBJECTIVE: The objective of our study was to prospectively evaluate the results of helical CT in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis undergoing orthotopic liver transplantation. SUBJECTS AND METHODS. Eighty-five patients with cirrhosis were studied preoperatively with biphasic helical CT. Arterial, portal, and equilibrium phase images were obtained after injection of 170 mL of contrast material at 5 mL/sec. The prospective CT interpretation was compared with pathologic results on a lesion-by-lesion basis. RESULTS: Pathologic examination found 85 cases of HCC in 51 patients. Helical CT enabled a correct diagnosis of HCC in 67 of 85 lesions for a sensitivity of 78.8%. HCC nodules were hypervascular in the arterial phase and hypovascular in the equilibrium phase in 63.5% (54/85) of patients. The false-negative rate was 21% (n = 18), and the positive predictive value was 88%. We had nine false-positive findings (11.8%) related to hemangiomas, transient hepatic attenuation differences, and regenerative nodules. Helical CT detected 61% (23/38) of lesions smaller than 2 cm and 93.6% (44/47) of lesions 2 cm or larger. CONCLUSION: Helical CT is a useful preoperative imaging technique in cirrhotic patients who are candidates for orthotopic liver transplantation, although it is relatively insensitive for detection of small lesions (< 2 cm).

Dual-phase helical CT of pancreatic adenocarcinoma: assessment of resectability before surgery.

OBJECTIVE: The aim of our study was to prospectively evaluate the accuracy of dual-phase helical CT in the preoperative assessment of resectability in patients with suspected pancreatic cancer using surgical and histopathologic correlation. SUBJECTS AND METHODS: Between January 1999 and December 2000, 76 patients with suspected pancreatic cancer underwent preoperative evaluation and staging with dual-phase helical CT (3-mm collimation for pancreatic phase, 5-mm collimation for portal phase). Iodinated contrast material was injected IV (170 mL at a rate of 4 mL/sec); acquisition began at 40 sec during the pancreatic phase and at 70 sec during the portal phase. Three radiologists prospectively evaluated the imaging findings to determine the presence of pancreatic tumor and signs of unresectability (liver metastasis, vascular encasement, or regional lymph nodes metastasis). The degree of tumor-vessel contiguity was recorded for each patient (no contiguity with tumor, contiguity of < 50%, or contiguity of > or =50%). RESULTS: Thirty-nine patients with pancreatic adenocarcinoma were surgically explored. Curative resections were attempted in 34 patients and were successful in 25. The positive predictive value for resectability was 73.5%. Nine patients considered resectable on the basis of CT findings were found to be unresectable at surgery because of liver metastasis (n = 5), vascular encasement (n = 2), or lymph node metastasis (n = 2). We found that the overall accuracy of helical CT as a tool for determining whether a pancreatic adenocarcinoma was resectable was 77% (30/39 patients). CONCLUSION: Dual-phase helical CT is a useful technique for preoperative staging of pancreatic cancer. The main limitation of CT is that it may not reveal small hepatic metastases.