Ultrasonographic-pathologic correlation of malignant hepatic masses

Liver tumors: utility of characterization at dual-frequency US

PURPOSE

To evaluate the potential utility of a technique for analysis of ultrasonographic (US) images obtained at two center frequencies in a phantom model and in a clinical study of liver tumors.

MATERIALS AND METHODS

A US phantom was built that contained target regions with polystyrene scatterers both smaller and larger than scatterers in the background material. High- and low-frequency US images of target regions were obtained, and changes in the contrast-to-noise ratio (CNR) of the targets relative to the background were determined. In a clinical evaluation, 12 hemangiomas, 13 liver metastases, one adenoma, and two hepatomas were evaluated in a similar manner, and the results were correlated with the histologic findings in resected lesions.

RESULTS

For targets containing scatterers smaller than those in the background, there was an increase in CNR of higher frequency images. The converse was true for target regions having scatterers larger than those in the background. Liver metastases generally showed an increase in CNR of higher frequency images, whereas hemangiomas generally showed somewhat decreased CNR of higher frequency images, differing significantly from metastases (P < .01-.001).

CONCLUSION

Changes in CNRs of relatively high- and low-frequency US images may give useful information on the frequency dependence of backscattering, which is descriptive of the histologic findings in lesions and which is not evident with conventional US images.

Pretreatment echogenicity of colorectal liver metastases predicts survival after hepatic cryotherapy

PURPOSE

There is currently no knowledge of the prognostic value of echogenicity of colorectal liver metastases in patients receiving no treatment, hepatic cryotherapy, or any other treatment modality. We sought to determine whether differences in echogenicity of colorectal liver metastases predict prognosis after hepatic cryotherapy.

METHODS

Between April 1990 and May 1997 the echogenicity of liver metastases was assessed intraoperatively in 48 patients undergoing cryotherapy for in situ destruction of colorectal liver metastases, with use of an Aloka machine with a 5-MHz scanner. Survival time was calculated by the Kaplan-Meier method, and the prognostic value of echogenicity and several other possible prognostic factors was tested with the log-rank test.

RESULTS

Thirty-three patients were found to have hyperechoic metastases. These patients had a favorable outcome, with a median survival time of 50 months, as compared with a median survival time of 24 months in the 15 patients with hypoechoic metastases (P = 0.0074). Regarding the remaining prognostic factors that were tested, only age less than 51 years, absence of involved nodes at primary resection, small diameter of liver metastases, and low preoperative serum carcinoembryonic antigen levels were associated with a favorable outcome.

CONCLUSION

We believe that this is an original description of the prognostic importance of echogenicity of colorectal liver metastases. Differences in echogenicity may be related to tumor biology. This will be addressed in further studies.

Direct correlation between sonography and histology of minute malignant hepatic nodule

To improve the qualitative diagnosis of ultrasonography (US) of minute malignant hepatic nodules, we studied the accurate and direct correlations between US and histopathology of 33 lesions using formalin-fixed autopsied livers. The target nodules were cut on the same plane as their US-image. The solid nests of malignant tumor without degeneration were hypoechoic on US. Hepatocellular carcinoma showed a wide variety of echo levels, from hypoechoic to isoechoic, and its images were more heterogeneous than those of other malignant lesions. The squamous cell carcinoma ranged from hypoechoic to hyperechoic according to the degree of keratinization. US may be useful for evaluating the degree of differentiation in squamous cell carcinoma. Marked mucin-production and "comedo" pattern seem to be histological factors of the hyperechoic US image of adenocarcinoma. This study may contribute to improve the quality of US-diagnosis of minute hepatic nodular lesions.

Radiological-pathological correlation of mass lesions in the liver

Thirty two human livers were removed at autopsy. These included 7 with space-occupying or tumour-like lesions, namely one with multiple cysts, three with haemangiomas, a lobated liver with multiple nodules of focal nodular hyperplasia, one with a metastasis which also had a small haemangioma and one with a hepatocellular carcinoma. Fine particle barium diluted 2:1 with water was injected by hand to fill the arterial system. In the lobated liver, the portal system was also filled. High definition radiographs of liver slices showed arteriographic detail not visible on angiography. The arteriographic appearances were correlated with the macroscopic and microscopic pathology. Liver cysts compress the arteries and arterioles but an apparent halo on the whole liver radiograph was shown to be spurious on a 1 cm thick high definition film. The small vessel pattern of haemangiomas is well demonstrated accounting for the hyperechoic sonograms but hypoechoic areas may also occur due to involution of or haemorrhage into tumours. The small lesions of focal nodular hyperplasia had a poor arterial supply but filled from a portal venous injection. Metastases had a peripheral network of small vessels, central necrosis and normal sized peripheral arteries with no large artery entering the tumour. In hepatocellular carcinoma, a large artery was demonstrated entering the tumour which was considerably more vascular than the metastases. These features should aid in distinguishing these lesions on sonography.

Implications of hyperechoic lesions in small hepatocellular carcinoma

Of 34 solitary small hepatocellular carcinomas (HCC) 2 cm in diameter or less, 13 with hyperechoic lesions were observed serially by sonography, and 11 of these were examined histologically. Serial examination showed that hypoechoic areas appeared at the periphery of or within, the hyperechoic tumor, and that these areas expanded more with tumor growth than the hyperechoic areas as if compressing or displacing the existing hyperechoic areas. Histologically, the hyperechoic lesions were composed mostly of well-differentiated cancer cells containing fat droplets, whereas the hypoechoic lesions were composed of cancer cells without fat droplets. In the two tumors that were formed almost completely of cancer cells showing fatty metamorphosis, cancer cells without fat droplets proliferated mainly in the periphery of the tumor. These findings suggest that, in hyperechoic HCC, cancer cells with fat droplets appear in the early stage of HCC, and probably change into concer cells without fat droplets by the time that a certain tumor size is reached, with gradual displacement by the latter type of cell during tumor growth.

Comparison of ultrasound and CT images of liver metastases

The US and CT images of liver metastases in 42 patients were systematically compared. Based on the US image the lesions were classified as non-echogenic, slightly echogenic, and markedly echogenic lesions, target lesions and lesions with diffuse alteration of structure. There was often discrepancy between the appearance of the US and CT images. The discrepancy was increased after contrast enhancement in non-echogenic and in slightly echogenic metastases and in metastases with diffuse alteration of echo structure and diminished in target lesions. The possible reasons for these differences are discussed.

Ultrasonically guided fine-needle biopsies in neoplastic liver disease: cytohistologic diagnoses and echo pattern of lesions

Sixty consecutive percutaneous fine-needle aspiration biopsies guided by ultrasound were performed without complications in patients with ultrasonically suspected focal or diffuse neoplastic liver disease. Evaluations of aspirated samples were based on cytologic examination of smear preparations (100%) combined with histologic examination of serial sectioned tissue fragments (81.7%). The overall accuracy rate of cytohistologic evaluations was 91.6% with a sensitivity of 92.2%, a specificity of 88.9%, and a high predictive value of positive results (cytology; 97.8%; histology, 100%). Percutaneous fine-needle aspiration biopsy guided by sonography proved to be a safe, useful, and highly accurate technique for making cytohistologic diagnoses of hepatic masses suspected of being malignant. No relationship was found between the various echo patterns of intrahepatic neoplastic lesions and cell type or primary site of tumor origin.

Echographic characteristics of malignant lymph nodes

We retrospectively reviewed the sonograms of 42 sequential patients for whom there was sonographic evidence of malignant lymphadenopathy. Twenty-three patients were known to have lymphoma, whereas 19 patients had lymph nodes involved with metastases. Each case was categorized according to the sonographic "texture" of the masses and the extent of sound transmission. Sonolucent masses were observed in 83% of the lymphoma cases and in 53% of patients with soft-tissue tumors. Nonetheless, a mixture of patterns was observed in nearly one-third of the cases. In 5 lymphoma patients there were enlarged lymph nodes that had all of the echographic qualities of simple cysts. Aside from this pattern, no correlation could be made between sonographic pattern and histologic diagnosis.