Intraluminal gel ultrasound and eco-color doppler: new tools for the study of colorectal cancer in mice.

AIM: Azoxymethane (AOM) is a potent carcinogen that induces colorectal cancer in mice. Intraluminal gel ultrasound is a technique based on the injection of gel into the rectum. This technique allows the colon to be straightened and to visualize and identify tumours. MATERIALS AND METHODS: Twenty female C57Bl/6J mice were injected intraperitoneally with 10 mg/kg of AOM one time per week for six weeks. The mice were monitored by ultrasound with a Vevo 2100 system. We evaluated the tumour area and tumour vasculature with Ecocolor-Doppler (ECD). Histological examination of sacrificed mice was employed as the standard protocol. RESULTS: After 40 weeks from the injection, ultrasound analysis revealed the presence of tumours in 50% of all mice. Ex vivo analysis revealed the presence of 57% true-positives and only one false-positive. In two mice, ultrasound did not reveale the presence of tumour due to its small dimension. This indicates that ultrasound is able to detect only tumours with sizes ≥3 mm². CONCLUSION: Ultrasound is a rapid examination compared to other diagnostic techniques. It has a good sensitivity when the tumours reach the dimensions of 3 mm² or more. Intraluminal gel allows for the tumour area to be evaluated when mice are still alive, while ECD allows for vasculature of intestinal walls and colorectal tumour to be evaluated.

Previously reported sonographic appearances of regional melanoma metastases are not likely due to necrosis.

OBJECTIVES: Sonography has proven to be a reliable tool in early detection of lymph node and in-transit cutaneous-subcutaneous metastases. Those metastases normally appear as hypoechoic or even anechoic lesions on sonography. It has been assumed that this appearance is due to necrosis of the lesions, but so far, that assumption has never been proven. The purpose of this retrospective study was to evaluate whether the hypoechoic appearance of melanoma metastasis is really due to tumor necrosis. METHODS: From a radiographic database, we retrieved 212 melanoma cases imaged with sonography over a 2-year period for disease staging or follow-up. We selected 37 positive cases with 84 nodal and extranodal (satellite and in-transit) metastatic lesions and reviewed the sonograms and pathologic slides (slides available for 40 of 84 lesions). We retrospectively assessed the vascularization pattern (color Doppler images available for 78 of 84 lesions), categorizing it as poor, intermediate, or consistent. We also looked for necrosis on the histopathologic material, categorizing it into scores of 0, 1, 2, and 3 for absence of necrosis, less than 20% necrosis, 20% to 40% necrosis, and greater than 40% necrosis, respectively. RESULTS: Despite their gray scale appearance, most melanoma lesions were vascularized on color Doppler imaging and showed limited necrosis at histopathologic analysis. Consistent vascularization on Doppler imaging, excluding substantial necrosis, was found in 44 of 78 lesions (56.4%). Poor vascularization on Doppler imaging, suggesting necrosis, was present in only 14% of the lesions. Substantial necrosis (scores of 2 and 3) was found pathologically in only 10% of the lesions. CONCLUSIONS: Necrosis seems to be an uncommon event in melanoma metastasis and is probably not the basis for its low-level echo pattern on sonography. The hypoechoic appearance is very typical of melanoma metastasis and is likely due to massive melanomatous infiltration (with the poor echo reflectivity of melanin). However, confirmation in larger pathologically proven series is required.

Central venous device-related thrombosis as imaged with MDCT in oncologic patients: prevalence and findings.

BACKGROUND: Venous thrombosis is a common occurrence in cancer patients, developing spontaneously or in combination with indwelling central venous devices (CVD). PURPOSE: To analyze the multidetector CT (MDCT) prevalence, appearance, and significance of catheter-related thoracic venous thrombosis in oncologic patients and to determine the percentage of thrombi identified in the original reports. MATERIAL AND METHODS: Five hundred consecutive patients were considered. Inclusion criteria were: presence of a CVD; availability of a contrast-enhanced MDCT; and cancer history. Exclusion criteria were: direct tumor compression/infiltration of the veins; poor image quality; device tip not in the scanned volume; and missing clinical data. Seventeen (3.5%) out of the final 481 patients had a diagnosis of venous thrombosis. RESULTS: Factors showing the highest correlation with thrombosis included peripherally-inserted CVD, right brachiocephalic vein tip location, patient performance status 3, metastatic stage disease, ongoing chemotherapy, and longstanding CVD. The highest prevalence was in patients with lymphoma, lung carcinoma, melanoma, and gynecologic malignancies. Eleven out of 17 cases had not been identified in the original report. CONCLUSION: CVD-related thrombosis is not uncommon in cancer patients and can also be observed in outpatients with a good performance status and a non-metastatic disease. Thrombi can be very tiny. Radiologists should be aware of the possibility to identify (or overlook) small thrombi.

Thrombosis and cancer: spectrum of multidetector CT findings in oncologic patients with thromboembolic disease. A pictorial review.

This article is a reasoned pictorial review illustrating the many faces of thrombotic and embolic disease developing in the cancer patient. From a clinical point of view, we particularly point out the importance of properly identifying this occurrence in its various presentations. From a radiological point of view, special emphasis is given to the wide spectrum of multidetector CT findings, to the clues of benign and malignant thrombus diagnosis, and to the potential interpretative pitfalls.

Sonography for locoregional staging and follow-up of cutaneous melanoma: how we do it.

OBJECTIVE: Sonography is being used with increasing frequency in the assessment of locoregional tumor spread in patients with melanoma. Nevertheless, to maximize its practical impact, sonography should be performed with state-of-the-art equipment, by specifically trained operators, and using a careful exploration technique and well-defined diagnostic criteria. In this "how I do it"-type article, we illustrate our practical approach to sonography of cutaneous melanoma. METHODS: We first illustrate the basic and advanced technical requirements; then we describe our exploration methods and our image interpretation approach; and finally, we report on our use of sonography as a guidance tool for interventional procedures. Special emphasis is given to methodological and interpretative clues, tricks, and pitfalls. RESULTS: Sonography can be used in the initial staging of patients with melanoma, particularly in the screening of patients scheduled for a sentinel lymph node biopsy procedure. Additionally, sonography can be used during patient follow-up to detect locoregional recurrence earlier than palpation. CONCLUSIONS: Sonography plays a growing role in the assessment of the superficial spread of melanoma. Nevertheless, state-of-the-art equipment and careful exploration by trained operators are necessary.

Contrast-enhanced sonography of the spleen.

Sonography is frequently the first imaging modality employed to evaluate the spleen. Nevertheless, splenic abnormalities frequently determine subtle changes in echogenicity and may be overlooked. Additionally, splenic disorders have a nonspecific appearance, mostly appearing as hypoechoic defects. Difficulties in differential diagnosis are not uncommon, with splenic infarctions resembling, for example, focal lesions. Color Doppler is usually of limited additional value. Instead, the spleen is optimally suited for contrast-enhanced sonography, being superficial, small, and homogeneous, and showing intense and persistent contrast enhancement. Scarcely evident abnormalities become evident after contrast medium injection. Additional information can be obtained in many clinical scenarios, including blunt trauma, left flank pain, lymphoma, and incidental detection of splenic abnormalities.