Recommendations
First, it should be stressed that clinical information and history of the patient are still the indispensable basis for the interpretation of all diagnostic modalities. Although very operator dependent, US often is the first choice for screening, especially if evaluation of vascular flow is required, as it is inexpensive, readily available and well accepted by the patients. The strength of CT scan remains in providing a good and detailed overview when assessment of the whole abdomen (and thorax) is needed.
CT is the standard test performed to image the liver, and CT examinations are generally acceptable in evaluating the majority of liver disease processes. In centers with particular expertise in MRI and the newest equipment, it is well recognized that MRI is superior to CT for the investigation of liver diseases. The greatest advantages of MRI over CT include:
- patients with suspected liver tumors with high vascularity, or blood flow. The most important tumor in this category is primary liver cancer (hepatocellular carcinoma or hepatoma),
- the preoperative evaluation of patients with liver metastases, and
- to distinguish between benign and malignant lesions of the liver. In this last category, patients with known primary tumors such as colon cancer very often may have liver lesions which are benign.
It makes a tremendous difference in patient management to know if these small lesions in the liver are either benign lesions or malignant liver lesions. The advantages of CT over MRI include that if individuals are unable to cooperate and hold their breath for 20 seconds, the image quality of CT surpasses the image quality and diagnostic ability of MRI. Patients in this category generally are older or more sick. CT is also the preferred modality in patients in the acute traumatic setting as it is easier to manage the patient in a CT machine than with a MRI machine since consideration has to be made in the setting of MRI that no iron-containing metal devices are brought within the imaging room. There are no similar constraints with CT.
The role of PET scanning for the liver currently is being established. Within the setting of abdominal and pelvic disease, PET scanning is effective at evaluating for the presence of disease outside the liver, in specific for the evaluation of tumor involvement of lymph nodes and for the distinction between scar tissue and recurrent cancer in patients who have been treated for rectal carcinoma. No one with metastatic colon and rectal cancer to the liver should under go liver directed therapy without a PET scan.
For tumors falling into the category of 'resectable disease' preoperative biopsy is usually unnecessary and should be reserved for exceptional cases. Laparoscopy in connection with laparoscopic sonography is advocated for staging of malignancies and for evaluation of all liver tumors (biopsy or laparoscopic resection) if malignancy or hepatocellular adenoma is suspected radiologically. Intraoperative ultrasound represents the best resolution of masses and anatomical conditions and should be considered mandatory for all hepatobiliary operations. All of these techniques are available at Vanderbilt Ingram Cancer Center (VICC).
