Current diagnostic imaging modalities of the liver

Diagnosis and treatment of benign focal liver lesions

BACKGROUND

With the routine use of improved imaging modalities, more benign liver lesions are detected nowadays. An accurate characterization of these incidental lesions may be a challenge, and frequently a biopsy or even unnecessary surgery is being performed. However, these interventions are not always to the benefit of the patient.

METHODS

A Medline search of studies relevant to imaging diagnosis and management of the most common, benign, solid and non-solid liver lesions was undertaken. References from identified articles were handsearched for further relevant articles. The authors' own experiences with benign liver lesions were also taken into account.

RESULTS

Although atypical imaging features are the exception rather than the rule, it is sometimes difficult to differentiate between benign and malignant lesions, and knowledge of their imaging features is essential if unnecessary work-up is to be avoided. The use of tissue-specific contrast media, which has clearly improved the accuracy of highly advanced radiological techniques, may be helpful during differential diagnosis. Once having established an accurate diagnosis, surgery is rarely indicated for a benign liver lesion because of its asymptomatic nature.

CONCLUSION

Knowledge of imaging features and a clear management strategy during diagnostic work-up, emphasizing the indications for surgery, will minimize the number of patients who have to undergo biopsy or unnecessary surgery.

An assessment of the accuracy of hepatic and splenic size based upon a clinician's physical examination, a radiologist's impression and the actual liver and spleen volumes calculated by CT scanning

OBJECTIVES

In this study, a radiologist's impression of liver and spleen size based on computed tomography (CT) images, calculated liver and spleen volumes as determined radiologically, and findings of a hepatologist were compared.

METHODS

One hundred and ninety-four consecutive subjects seen by a hepatologist were evaluated clinically and radiologically. Liver and spleen volumes were calculated based on CT images and compared to radiologist's impression and to expected liver volume based on body weight. Covariate analysis was used to determine the relationships between different variables, and a value of P < 0.05 was considered to be significant.

RESULTS

Liver volume calculated on the basis of CT scans correlated to liver size based on the hepatologist's clinical exam but not to the radiologist's impression of liver size. In contrast, spleen volume based on CT scans, splenic size based upon radiologist's impression, and clinician's assessment all correlated well.

CONCLUSIONS

A variety of biases determine and/or affect the radiologist's assessment of liver size but not of splenic size.

Real time contrast enhanced ultrasonography in detection of liver metastases from gastrointestinal cancer

Background

Contrast enhanced ultrasound (CEUS) is an imaging technique which appeared on the market around the year 2000 and proposed for the detection of liver metastases in gastrointestinal cancer patients, a setting in which accurate staging plays a significant role in the choice of treatment.

Methods

A total of 109 patients with colorectal (n = 92) or gastric cancer prospectively underwent computed tomography (CT) scan and conventional US evaluation followed by real time CEUS. A diagnosis of metastases was made by CT or, for lesions not visibile at CT, the diagnosis was achieved by histopathology or by a malignant behavior during follow-up.

Results

Of 109 patients, 65 were found to have metastases at presentation. CEUS improved sensitivity in metastatic livers from 76.9% of patients (US) to 95.4% (p <0.01), while CT scan reached 90.8% (p = n.s. vs CEUS, p < 0.01 vs US). CEUS and CT were more sensitive than US also for detection of single lesions (87 with US, 122 with CEUS, 113 with CT). In 15 patients (13.8%), CEUS revealed more metastases than CT, while CT revealed more metastases than CEUS in 9 patients (8.2%) (p = n.s.).

Conclusion

CEUS is more sensitive than conventional US in the detection of liver metastases and could be usefully employed in the staging of patients with gastrointestinal cancer. Findings at CEUS and CT appear to be complementary in achieving maximum sensitivity.

Treatment of hepatic metastases from colorectal cancer: Many doubts, some certainties

About 50% of patients with colorectal cancer (CCR) are destined to develop hepatic metastases during the course of the disease. Surgery is currently the only potentially curative treatment with a five year survival rate after hepatectomy from 26% to 49%. The criteria for resectability are now less rigid than in the past and the tendency to adopt a more aggressive treatment of metastatic lesions is the rule. Systemic infusion chemotherapies based on 5-fluorouracil (5-FU), oxaliplatin (OHP) and irinotecan (CPT-11) are well tolerated and have been shown to be effective in non-operable patients. These regimens allow surgery for patients who are initially not suitable for resection, giving them a probability of survival at five years similar to that of patients operated on at diagnosis. Intra-arterial infusion chemotherapy (HAI) is very effective in inducing objective responses, but is costly, difficult to manage and encumbered by major side effects, so that its application is necessarily limited to centres with specific experience. However, despite the broader criteria and recent advances of chemotherapy, surgery is not possible in most patients. The role of other local therapeutic techniques like cryosurgery (CS) and radiofrequency ablation (RF), alone or combined with surgery or chemotherapy, is not yet established in a multidisciplinary therapeutic approach. Roughly two thirds of patients relapse during the first two years after surgery suggesting appropriate post-operative chemotherapy treatment after hepatic resection may be indicated, but no randomised studies have been published to date. In case of relapse, another hepatectomy should be considered. The role of novel targeted therapies in pre-operative, post-operative and palliative management has yet to be evaluated.

Focal liver lesions

Preview Solid focal lesions of the liver can present numerous diagnostic challenges, and once diagnosis is made, careful decision making is needed to assure cost-effective management. In this article, the authors consider five solid lesions: hemangioma, focal nodular hyperplasia, liver cell adenoma, primary hepatocellular carcinoma, and metastatic cancer. Cystic lesions are assessed in a companion article on page 149.