Real-time ultrasonography-computed tomography fusion imaging for staging of hepatic metastatic involvement in patients with colorectal cancer: initial results from comparison to US seeing separate CT images and to multidetector-row CT alone.

OBJECTIVES: To prospectively evaluate the role of real-time ultrasonography (US)-computed tomography (CT) fusion imaging (US-CT) in comparison with US seeing separate CT images (US + CT) and multidetector-row CT (MDCT) for the correct staging of hepatic metastatic involvement in patients with colorectal cancer. METHODS: Sixty-four patients with newly diagnosed colorectal cancer and who were referred for abdominopelvic staging before primary tumor resection underwent same-day MDCT, US + CT, and US-CT. Examinations were evaluated on-site by 2 investigators in consensus. Investigators recorded the size and location of detected lesions on segmental liver maps, classified them as being benign, malignant, or indeterminate, and finally assessed the M stage of the liver as being M0, M1, or Mx (indeterminate). All patients underwent surgical exploration including intraoperative US. Reference standard diagnosis was based on findings at surgery, intraoperative US, histopathology, and MDCT follow-up imaging. Differences among investigated modalities were analyzed using McNemar's test. RESULTS: The reference standard verified 109 (45 < or = 1 cm) hepatic lesions in 25 patients, including 65 (25 < or = 1 cm) metastases in 16 patients (M1). Regarding the 45 < or = 1 cm liver lesions, rates for detection were significantly higher (P < 0.05) for MDCT (80%, 36/45) and US-CT (77.8%, 35/45) than for US + CT (64.4%, 29/45); the rate for correct classification by US-CT (71.1%, 32/45) was significantly higher than for US + CT (48.9%, 22/45) and MDCT (31.1%, 14/45) (all P < 0.05). On patient-based analysis, specificity of MDCT (85.4%, 41/48) was significantly lower (P < 0.05) than for US-CT (97.9%, 47/48) and US + CT (93.7%, 45/48); the positive predictive value of MDCT (63.1%, 12/19) was not significantly different (P = 0.27) compared with US + CT (82.3%, 14/17) but significantly lower (P < 0.05) than for US-CT (93.7%, 15/16). In 13 patients (59 lesions) with only benign (stage M0) or coexistent benign and malignant lesions (stage M1), indeterminate lesion ratings and indeterminate liver stagings (Mx) occurred both significantly lower (P < 0.05) with US-CT (3.4%, 2/59; and 0%, 0/13) than with US + CT (11.9%, 7/59; and 23.1%, 3/13) or with MDCT (30.5%, 18/59; and 53.8%, 7/13). CONCLUSIONS: Based on these initial diagnostic experiences, complementary US-CT fusion imaging of small CT-indeterminate liver lesions may have value in staging patients with colorectal cancer, focusing on patients who were likely to harbor only benign or coexisting benign and malignant liver lesions and in whom change of M staging would change the clinical management.

Differentiation of benign from malignant focal splenic lesions using sulfur hexafluoride-filled microbubble contrast-enhanced pulse-inversion sonography.

OBJECTIVE: The purpose of our study was to evaluate whether sonographic characterization of focal splenic lesions could be improved by using low mechanical index pulse-inversion sonography after sulfur hexafluoride-filled microbubble injection. MATERIALS AND METHODS: One hundred forty-seven splenic lesions (68 benign, 79 malignant) in 147 patients (81 men, 66 women; mean age, 51 years) underwent baseline gray-scale sonography and sulfur hexafluoride-enhanced low-acoustic-power pulse-inversion sonography (mechanical index < 0.1). Two site investigators assessed in consensus lesion and splenic enhancement during arterial and parenchymal phases. Four readers (readers 1 and 2, blinded; and readers 3 and 4, unblinded to clinical data) independently reviewed baseline and contrast-enhanced sonograms and provided confidence rating for diagnosis of malignancy or benignancy. Accuracy, sensitivity, specificity, positive and negative predictive values, and areas under the receiver operating characteristic curves (A(z)) were calculated by considering biopsy results or splenectomy (51 patients) or CT or MR images followed by serial sonography 6-12 months apart (96 patients) as reference standards. RESULTS: Benign lesions appeared predominately non- or isoenhancing relative to splenic parenchyma, whereas malignant lesions appeared predominately progressively hypoenhancing. For correct diagnosis of benignancy or malignancy, review of contrast-enhanced sonography after baseline sonography yielded significantly improved diagnostic performance (overall accuracy, 51%, 43%, 70%, and 74% before vs 83%, 81%, 92%, and 91% after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively) and significantly improved diagnostic confidence (A(z), 0.770, 0.678, 0.900, and 0.917 before vs 0.935, 0.917, 0.984, and 0.959 after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively). CONCLUSION: Sulfur hexafluoride-filled microbubble-enhanced sonography improves characterization of focal splenic lesions with and without the availability of clinical data.