The value of intraoperative ultrasound during hepatic resection compared with improved preoperative magnetic resonance imaging

The role of contrast-enhanced ultrasound for focal liver lesion detection: an overview

The development of new ultrasound (US) contrast agents and sonographic techniques has considerably improved the possibilities of ultrasound in the assessment of liver tumors. An overview is given on diagnostic potential of contrast-enhanced US (CEUS) and real-time low mechanical index technique in the detection of various focal liver lesions compared with computed tomography, magnetic resonance imaging or intraoperative US. In two of our own studies that included 100 patients each we showed an increase of correct findings in CEUS compared with B-mode US from 64% to 87% and from 67% to 84% as confirmed by intraoperative evaluation of the liver. Especially after chemotherapy and in the case of small metastases, significantly more metastases were correctly detected by CEUS compared with B-mode US. These results and clinical study results in the literature show that CEUS allows tumor detection and direct visualization of the tumor vascularity and put contrast-enhanced sonography among recommended noninvasive imaging methods for focal liver lesions with improvements in diagnostic strategy.

Image-guided surgery of liver metastases by three-dimensional ultrasound-based optoelectronic navigation

BACKGROUND

Vessel-oriented surgery and tumour-free resection margins are essential for resection of liver metastases to preserve liver parenchyma and improve oncological outcome. Preoperative three-dimensional models reconstructed from imaging data could facilitate surgical planning with the use of navigation technology.

METHODS

Thirty-three patients with central and/or impalpable liver metastases were scheduled for navigated hepatic resection. Intraoperative three-dimensional ultrasonography and an infrared-based optical tracking system were used for data registration and image-guided surgery. Postoperative three-dimensional data were compared with the preoperative virtual surgical plan to assess the accuracy of navigation, and clinical results were compared with those of a matched control group of 32 patients.

RESULTS

Navigation was successful in 32 of 33 patients. Realization of the preoperative plan and R0 resection was achieved in 30 of these 32 patients. The median discrepancy between the planned and actual vascular dissection level was 6 (range 0-11) mm. There was a reduced rate of R1 resection in the navigated group compared with the control group (two versus four patients), and more parenchyma was preserved.

CONCLUSION

Three-dimensional ultrasound-based optoelectronic navigation technology improves intraoperative orientation and enables parenchyma-preserving surgery with high precision.

Detection of hepatic metastases from colorectal carcinoma: comparison of histopathologic features of anatomically resected liver with results of preoperative imaging

GOALS

The specificity and sensitivity of intravenous-enhanced multidetector row computed tomography (MDCT), superparamagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI), multidetector row computed tomography with arterioportography combined with multidetector row computed tomography with hepatic arteriography (CTAP/CTHA), and intraoperative ultrasonography (IOUS) for detecting hepatic metastases from colorectal carcinoma were evaluated based on histopathologic examination of resected livers.

STUDY

MDCT, SPIO-MRI, CTAP/CTHA, and IOUS were performed routinely to determine surgical indications and methods in patients with hepatic metastases from colorectal carcinoma. The resected liver specimens were then cut serially into sections 3 to 5 mm thick for routine histologic examination.

RESULTS

Fifty metastatic lesions were detected by histopathologic study of a large amount of anatomically resected liver from 8 patients with colorectal liver metastasis. The tumors ranged in size from 3 to 53 mm (mean 13.8 mm) and 26 lesions (52%) were less than 10 mm in diameter. Histopathologic examination of the resected liver specimens showed that CTAP/CTHA was the most sensitive imaging modality, followed in order by IOUS, SPIO-MRI, and MDCT. Among all the tumors detected by CTAP/CTHA, SPIO-MRI overlooked 5, but all of the tumors detected by SPIO-MRI were also detected by CTAP/CTHA. The number of metastatic liver tumors detected differed significantly among MDCT, SPIO-MRI, and histopathologic examination. One false-positive lesion was detected by IOUS.

CONCLUSIONS

CTAP/CTHA is a useful preoperative imaging modality for detecting small hepatic metastases from colorectal carcinoma.

Feasibility of navigated resection of liver tumors using multiplanar visualization of intraoperative 3-dimensional ultrasound data

BACKGROUND

Intraoperative ultrasound is widely used in liver surgery, but primarily for diagnostic purposes. We have developed and evaluated a system for navigated liver resections using on intraoperatively acquired 3-dimensional (3D) ultrasound data.

METHODS

Navigation technique based on 3D ultrasound and an optical tracking system. Accuracy of the system was validated experimentally in a tumor model. Subsequently, clinical application was evaluated in 54 patients for resection of central liver tumors. Clinical feasibility and accuracy of the navigation technique were assessed with respect to practicability, adequacy of visualization, and precision of navigated resection (free margin).

RESULTS

Evaluation of the system in the tumor model showed a significant increase of the accuracy of navigated resections compared with conventional resection (P < 0.05). Clinical application of 3D ultrasound-based navigation was feasible in 52 of 54 patients. Sufficient visualization was obtained with 2 orthogonal section planes. This navigation strategy provided complete anatomic orientation and accurate position control of surgical instruments. Mean histologic resection margin was 9 mm with a maximum deviation of 8 mm from the planned virtual resection margins.

CONCLUSIONS

Optoelectronic navigation with section mode visualization in 2 orthogonal planes does sufficiently display intraoperative 3D data and enables accurate ultrasound-based navigation of liver resections.

Intraoperative ultrasonography in detecting and assessment of colorectal liver metastases

OBJECTIVE

to assess the clinical value of intraoperative ultrasonography (IOUS) in detecting and assessment of liver metastatic tumours in colorectal cancer patients.

METHODS

a study is a retrospective analysis of 388 patients operated on for colorectal carcinoma between 1997 and 2004. In all the patients intraoperative ultrasound was performed. The authors analyzed of sensitivity, specificity, PPV, NPV and accuracy of pre- and intraoperative ultrasonography in detecting and staging of colorectal metastatic lesions.

RESULTS

Intraoperative ultrasonography showed the highest sensitivity, specificity and accuracy in both, tumor detection (99.1, 98.5 and 98.9%, respectively) and assessment (95.4, 99.5 and 99.1%, respectively). Overall sensitivity of IOUS was significantly better in detection and staging compared with preoperative ultrasonography 91.1 and 72.2%, respectively).

CONCLUSIONS

IOUS should be used as routine diagnostic modality in colorectal cancer patients with hepatic metastases or suspected metastases. Transabdominal ultrasonography cannot be used as the only diagnostic tool in the evaluation of liver lesions, but may be helpful in preoperative screening.

Radiological staging of colorectal liver metastases

Rapid advances in imaging technology have improved the detection, characterization and staging of colorectal liver metastases. Multi-modality imaging approach is usually the more useful in staging colorectal liver metastases. Multi-detector computed tomography (MDCT) remains the main imaging modality for preoperative planning, lesion detection and tumour surveillance. Magnetic resonance imaging (MRI) and contrast enhanced ultrasonography (US) are invaluable in problem solving for characterization indeterminate lesions, while contrast enhanced intra-operative ultrasound (CE-IOUS) may be the new gold standard staging tool prior to liver resection. Ultimately, the imaging strategy has to be tailored to the clinical situation to obtain the most relevant information for optimal use of available imaging resources.

Vascular endothelial growth factor does not improve liver regeneration and survival after 90% subtotal liver resection

AIM

Vascular endothelial growth factor (VEGF) has been shown to stimulate liver regeneration after 70% partial hepatectomy (PH). It is unclear, however, whether exogenous administration of VEGF can also be used to improve liver regeneration and survival after 90% subtotal liver resection. The aim of this study was to determine the effect of exogenous and endogenous VEGF after 90% subtotal hepatectomy (SH).

METHODS

Rats were subjected to 90% SH and treated with VEGF, anti-VEGF or NaCl. Postoperatively (3 h - 5 days) liver body weight ratio (LBR), hepatocyte proliferation and biochemical markers were assessed. ELISA was performed to measure protein levels for VEGF. Gene expression was determined by customized cDNA arrays and quantitative RT-PCR.

RESULTS

Administration of VEGF did not enhance LBR or hepatic proliferation, or reduce the serum parameters. VEGF levels were the highest in VEGF-treated animals. The overall survival after 90% SH reached 78% in VEGF-treated animals, but did not differ significantly from that of anti-VEGF or NaCl-treated animals (74% and 75%, respectively). Gene expression analysis showed a modulation of anti-apoptotic and cell cycle control genes that was independent of VEGF.

CONCLUSIONS

In contrast to PH, liver regeneration and survival after SH cannot be modulated by VEGF. This indicates that the relevant mechanisms that stimulate liver regeneration after hepatectomy at least partially depend upon the extent of liver resection.

A cost-utility analysis of treatments for malignant liver tumours: a pilot project

BACKGROUND

Hepatic resection is the standard treatment for colorectal liver metastases when feasible. Techniques such as radiofrequency ablation (RFA) have been the subject of ongoing research in hopes of achieving a similar survival to that achieved with hepatic resection, but with less morbidity and better quality of life (QOL). The aim was to to generate a hypothesis concerning the cost-utility of various treatments that may be further tested with randomized trials in the future.

PATIENTS AND METHODS

This was a prospective, non-randomized pilot study comparing the cost-utility of hepatic resection, RFA, systemic chemotherapy, and symptom control alone for colorectal liver metastases. All patients with newly diagnosed liver malignancies were eligible. QOL was measured serially with the Health Utilities Index. Costs, in 2001 Canadian dollars, were captured from the viewpoint of society in general.

RESULTS

In all, 40 patients were enrolled in the study: 7 underwent hepatic resection, 7 underwent RFA (sometimes in combination with resection), 20 received systemic chemotherapy, and 6 received symptom control alone. Liver resection appeared to be the most effective approach, with an average benefit of 2.58 QALYs (quality-adjusted life years) compared with 1.95 QALYs for RFA, 1.18 QALYs for chemotherapy, and 0.82 QALYs for symptom control alone, resulting in cost-utility ratios of $7792, $8056, $12,571, and $4788 per QALY, respectively.

DISCUSSION

The cost-utility of hepatic resection and RFA appeared similar even though patients receiving RFA had more advanced disease. The role of RFA is still being defined; however, if long-term survival proves to be promising, then this study lends support to the conduct of randomized controlled trials in the future.

Current role of radiofrequency ablation for the treatment of colorectal liver metastases

BACKGROUND AND METHOD

This paper reviews the current status of radiofrequency ablation in the treatment of colorectal liver metastases. Relevant studies with at least ten patients that reported rates of complete tumour ablation, local recurrence, or survival from 1 to 5 years after treatment were included in the review.

RESULTS AND CONCLUSION

Only six studies that reported at least 3-year survival were identified, with results ranging from 37 to 58 per cent. Some of these figures are promising, given that the patients were considered to have unresectable disease. However, available evidence is limited and hepatic resection remains the standard of care when feasible; radiofrequency ablation cannot be considered an equivalent. Radiofrequency ablation does, however, appear to have a role in treating unresectable disease, and may also be used in conjunction with resection to extend its limits.

Intraoperative US of the liver: techniques and clinical applications

Intraoperative ultrasonography (US) of the liver provides the operating surgeon with useful real-time diagnostic and staging information that may result in an alteration in the planned surgical approach. Current applications for intraoperative US of the liver include tumor staging, metastatic survey, guidance for metastasectomy and various tumor ablation procedures, documentation of vessel patency, evaluation of intrahepatic biliary disease, and guidance for whole-organ or split-liver transplantation. To obtain the most useful information with intraoperative US, the sonographer should use a dedicated transducer and a scanning method appropriate for the purpose of the examination. In addition, the radiologist must be familiar with the relevant intraoperative and vascular anatomy and the spectrum of normal and abnormal findings and should be alert to the pitfalls that frequently occur in the interpretation of intraoperative US images of the liver.

Follow-up result afters negative findings on unenhanced hepatic MR imaging for hepatic metastasis from rectal cancer

OBJECTIVE

To assess the follow-up results after negative findings on unenhanced hepatic MR imaging in rectal cancer patients who have undergone locally curative surgery.

MATERIALS AND METHODS

From all pertinent imaging reports and medical records, we selected 255 patients who had negative results on unenhanced hepatic MR imaging. When selecting patients who had undergone curative resection, the following patients were excluded from the study: 1) patients in whom extrahepatic metastases were detected on preoperative staging work-ups, 2) patients in whom the surgery was judged to be non-curative due to peritoneal seeding or local aggressiveness. Cases with follow-up periods of less than 18 months were also excluded, as these cases were considered insufficient to confirm the negative outcomes. Thus, a total of 149 patients were ultimately enrolled in our study. The follow-up results of unenhanced MR imagings were assessed according to the assumption that the newly developed hepatic metastases had been false-negative lesions on preoperative MR image.

RESULTS

During a median follow-up period of 29.3 months, 25 hepatic metastases were detected in 13 patients (8.7%), which indicated a negative predictive value of 91.3%.

CONCLUSION

Unenhanced hepatic MR imaging provides a high negative predictive value with regard to the detection of hepatic metastasis in the preoperative evaluation of rectal cancer.

Comparison of CT During Arterial Portography and MR During Arterial Portography in the Detection of Liver Metastases

OBJECTIVE

This study compared MR during arterial portography (MRAP) with CT during arterial portography (CTAP) with regard to the detection and differentiation of liver metastases before surgery.

MATERIALS AND METHODS

Fifteen patients with liver metastases were enrolled before surgery according to the guidelines of our institutional review board and good clinical practice. After mesentericography, unenhanced scans (Volume Zoom) were performed initially. For CTAP, the contrast medium was injected through the superior mesenteric artery. Images were acquired in portal and delayed enhancement. The MR protocol (1.5 T; Magnetom Symphony) started with T1-weighted fast low-angle shot (FLASH) T2-weighted turbo spin echo (TSE). MRAP followed with gadolinium-enhanced dynamic T1-weighted 3D FLASH. Delayed-phase T1-weighted 2D FLASH axial images were performed 2 min after IV injection of the contrast medium. Qualitative and quantitative evaluation of CTAP and MRAP was performed by three blinded radiologists regarding the number of lesions and their size, localization, and differential diagnosis.

RESULTS

The overall sensitivity in detecting liver metastases was 97% with MRAP and 93% with CTAP (p > 0.05, not significant [n.s.]). The specificity was calculated to be 97% for MRAP and 82% for CTAP (p < 0.0001, statistically significant [s.s.]). The differences in sensitivity were more accentuated if only lesions 10 mm or smaller were considered (95% vs 88%, p > 0.05, n.s.), for which the respective specificities were 95% and 80% (p < 0.0014, s.s.). Improvements in sensitivity and specificity were associated with a higher lesion-to-liver contrast-to-noise ratio (59.4 +/- 51.0 for MRAP vs 10.4 +/- 7.3 for CTAP) and resulted in higher diagnostic confidence in the differential diagnosis of liver lesions (p < 0.001, s.s.) and better interobserver agreement (median kappa value, 0.88 vs 0.63).

CONCLUSION

MRAP proved to be a reliable method in the preoperative detection of small liver metastases in particular, with a higher sensitivity and specificity than CTAP. If organizational difficulties of MRAP can be overcome, MRAP could be considered instead of CTAP in the preoperative invasive evaluation of metastatic liver disease.

Potential value of contrast-enhanced intraoperative ultrasonography during partial hepatectomy for metastases: an essential investigation before resection?

OBJECTIVE

The aim of the study was to assess the clinical value of contrast-enhanced intraoperative ultrasound (CE-IOUS) as a novel tool in the hepatic staging of patients undergoing liver resection.

METHODS

Sixty patients scheduled to undergo liver resection for metastatic disease were studied. Preoperative staging with contrast-enhanced CT and/or MR scans was performed within 2 to 6 weeks of operation. Following exploration, intraoperative ultrasound (IOUS) was performed using an HDI-5000 scanner (Philips) and a finger-probe with pulse inversion harmonic (PIH) capability. CE-IOUS in the PIH mode was performed in a standardized protocol (low MI: 0.02-0.04) after intravenous injection of 3-4 mL of SonoVue (Bracco spa, Milan); all detected lesions on precontrast and postcontrast scans were counted and mapped. Any alteration in surgical management was documented following CE-IOUS compared with IOUS.

RESULTS

Three patients were excluded due to disseminated disease on exploration. CE-IOUS was significantly more sensitive than CT/MR and IOUS in detecting liver metastases (96.1% versus 76.7% and 81.5%, respectively) (P<0.05); it altered surgical management in 29.8% (17 of 57) of cases, due to 1) additional metastases in 19.3% (11 of 57), 2) less metastases in 3.5% (2 of 57), 3) benign lesions wrongly diagnosed as metastasis on IOUS/CT in 5.3% (3 of 57), and 4) vascular proximity in 1.8% (1 of 57). Management was unchanged in 70.2% (40 of 57) despite additional lesions detected in 3.5% (2 of 57) and benign lesion wrongly diagnosed on IOUS and CT as metastasis in 1.8% (1 of 57). CE-IOUS altered combined IOUS/CT/MR staging in 35.1%.

CONCLUSION

These preliminary results suggest CE-IOUS is an essential tool prior to liver resection for metastases.

Intraoperative ultrasonography in open and laparoscopic abdominal surgery: an overview

This article reviews the current state of intraoperative ultrasonography in open surgery (IOUS) and laparoscopic surgery (LUS). The review is based on extensive study of data published (Pubmed search) and on 25 years of personal experience with intraoperative ultrasonography. The main application areas of IOUS and LUS and its use during liver, biliary tract, and pancreatic surgery are discussed. The benefits and limitations as well as future expectations with regard to the existing and emerging applications also are discussed. New developments in ultrasound technology and the increasing experience of surgeons in ultrasonography secure the future for IOUS and LUS.

The routine use of intra-operative ultrasound in patients with colorectal cancer improves the detection of hepatic metastases

INTRODUCTION

Up to one fifth of patients with carcinoma of the colon have occult liver metastases at the time of presentation. Intra-operative hepatic ultrasonography might improve disease staging. We report the use of intra-operative ultrasonography (IOUS) in routine clinical practice over a five-year period.

METHOD

Seventy-six patients with colorectal carcinoma (F 21, M 55) of median age 67 years (range 43-89 years) for whom full data were available had IOUS at the time of colonic resection. All patients had had a computerized tomography (CT), magnetic resonance imaging (MRI) or ultrasonography (USS).

RESULTS

Of 76 patients, 10 had a Dukes A, 32 had a Dukes B and 34 a Dukes C carcinoma. In 20 patients IOUS detected lesions not seen on pre-operative scanning including 11 metastases (one suitable for resection), seven benign hepatic cysts and two were benign hepatic nodules. Forty-nine patients have remained free of disease and 25 have died with systemic disease (mean survival 10 months, range 2-24 months). In the seven patients diagnosed as having hepatic cysts at IOUS two have died of systemic disease. The remaining patients (n=12) who died with systemic disease had a negative IOUS.

CONCLUSION

IOUS increases diagnostic yield but a significant proportion of patients with occult hepatic metastases are not detected. IOUS improves disease staging in some patients refining the indications for adjuvant therapy and enhancing the estimate of prognosis and improving decision-making.

Accuracy of preoperative imaging of hepatic tumors with helical computed tomography

BACKGROUND

The accuracy of preoperative computed tomography (CT) scans in the era of modern imaging techniques with helical, high-resolution CT has not been adequately assessed. We reviewed the data from our departmental prospective database with the hypothesis that intraoperative ultrasonography (IOUS) still detects more hepatic tumors than are evident on preoperative helical CT scans.

METHODS

All patients who underwent surgical resection and/or radiofrequency ablation of primary or metastatic hepatic tumors between January 2001 and July 2002 were included in the review. All patients had preoperative helical CT imaging followed by hepatic IOUS. The number of malignant lesions and evidence of local disease identified by the preoperative CT scan versus IOUS and surgical exploration were compared.

RESULTS

In this time period, 250 patients underwent surgical resection and/or radiofrequency ablation of hepatic tumors. In 67 (27%) of these patients, IOUS identified more hepatic tumors than were seen on preoperative helical CT scan. In eight patients (3%), CT underestimated local extension of the disease into the diaphragm. The incidence of inaccurate preoperative prediction of the extent of disease increased significantly with a greater number of hepatic tumors.

CONCLUSIONS

IOUS identified additional hepatic tumors in 27% of patients who underwent hepatic resection after state-of-the-art preoperative CT imaging. This study provides evidence that IOUS remains an essential part of the complete assessment of hepatic malignancies in patients who receive surgical treatment.

[The impact of intra operative ultrasound in metastases liver surgery]

BACKGROUND

Twenty-five to 50% of the patients with hepatic metastases are potential candidates for curative surgery. Intraoperative ultrasound has been employed to guide the surgery.

AIM

To evaluate this method in liver surgeries and compare it to other imaging methods.

PATIENTS AND METHODS

Thirty-five patients (20 females, with median age of 56 years) with hepatic metastases were prospectively studied between February 2001 and July 2003. Patients had as primary tumors: colorectal cancer (24), neuroendocrine tumors (3), renal cell carcinoma (2), melanoma (2), others (4). Each patient was submitted to at least: computed tomography (30), ultrasonography (14) and magnetic resonance imaging (8). Intraoperative ultrasound was performed in all patients in order to detect liver nodules. The number and location of liver lesions were compared to preoperative results.

RESULTS

Intraoperative ultrasound was useful in 23 (65.6%) of the 35 surgeries and changed the planned surgical strategy in 9 (25.7%). There was a statistical significant correlation between the mean number of nodules identified by ultrasonography, computed tomography, magnetic resonance imaging and intraoperative ultrasound. We found no statistical difference between magnetic resonance imaging and intraoperative ultrasound in identifying hepatic nodules. Fifty-five nodules were submitted to histological evaluation, the gold standard method and 52/55 (94.5%) were identified by intraoperative ultrasound. Intraoperative ultrasound identified 91.6% of the smaller than 1.5 cm lesions, ultrasonography identified 15.0% of them, computed tomography 33.3% and magnetic resonance imaging 66.6%.

CONCLUSIONS

Intraoperative ultrasound is crucial in the evaluation and decision making in hepatic surgery. Intraoperative ultrasound presents the highest sensibility in the detection of hepatic nodules compared to other imaging methods, especially for small lesions.

Management of hepatic metastases from colorectal cancer

The majority of hepatic metastases in the United States occur in patients with a primary colorectal malignancy. Advances in technology combined with increasing surgeon experience have broadened the treatment options available for hepatic metastases from colorectal cancer. Surgical resection is the most effective therapy for metastatic colorectal cancer isolated to the liver. The aim of this article is to discuss the role of locally aggressive treatment options including resection, ablation, and regional chemotherapy in the management of patients with metastases from colorectal cancer.

In vitro chronic hepatic disease characterization with a multiparametric ultrasonic approach

Although, high resolution, real-time ultrasonic (US) imaging is routinely available, image interpretation is based on grey-level and texture and quantitative evaluation is limited. Other potentially useful diagnostic information from US echoes may include modifications in tissue acoustic parameters (speed, attenuation and backscattering) resulting from disease development. Changes in acoustical parameters can be detected using time-of-flight and spectral analysis techniques. The objective of this study is to explore the potential of three parameters together (attenuation coefficient, US speed and integrated backscatter coefficient-IBC) to discriminate healthy and fibrosis subgroups in liver tissue. Echoes from 21 fresh in vitro samples of human liver and from a plane reflector were obtained using a 20-MHz central frequency transducer (6-30 MHz bandpass). The scan plane was parallel to the reflector placed beneath the liver. A 30 x 20 matrix of A-scans was obtained, with a 200-microm step. The samples were classified according to the Metavir scale in five different degrees of fibrosis. US speed, attenuation and IBC were estimated from standard methods described in the literature. Statistical tests were applied to the results of each parameter individually and indicated that it was not possible to identify all the fibrosis groups. Then a discriminant analysis was performed for the three parameters together resulting in a reasonable separation of fibrotic groups. Although the number of tissue samples is limited, this study opens the possibility of enhancing the discriminant capability of ultrasonic parameters of liver tissue disease when they are combined together.

Intraoperative ultrasonography of the liver in patients with abdominal tumors: a new approach

OBJECTIVES

To compare liver intraoperative ultrasonography (IOU), computed tomography (CT), preoperative ultrasonography (USG), and intraoperative inspection and palpation in the detection of hepatic lesions in patients with abdominal tumors.

METHODS

This was a prospective study including 60 patients with abdominal tumors evaluated by USG, CT, inspection and palpation, and hepatic IOU during exploratory laparotomy. Sensitivity, specificity, and positive and negative predictive values for all methods were calculated. Agreement of methods with histopathologic results was calculated by kappa statistics and the Spearman coefficient.

RESULTS

Of the 60 patients, 49 (81.6%) had positive findings for hepatic lesions. Lesions could not be counted in 3 patients. The 46 remaining cases were diagnosed by histologic examination. Sensitivity, specificity, and positive and negative predictive values were 42.9%, 88.9%, 90%, and 40% for USG; 59.5%, 77.8%, 86.2%, and 45.2% for CT; 69.0%, 88.9%, 93.5%, and 55.2% for inspection and palpation; and 90.5%, 77.8%, 90.5%, and 77.8% for IOU, with histologic examination used as a criterion standard. Fair to moderate agreement was found for USG, CT, and inspection and palpation (kappa = 0.24, 0.31, and 0.49, respectively). Substantial agreement was found for IOU (kappa = 0.68). Changes in surgical strategy were made in 19 (41.3%) of the 46 cases with positive findings.

CONCLUSIONS

High sensitivity associated with substantial agreement with histopathologic findings shows that IOU is an indispensable evaluation method for hepatic screening in patients with abdominal tumors who undergo laparotomy and should become a routine procedure wherever available.

Intraoperative US in Patients Undergoing Surgery for Liver Neoplasms: Comparison with MR Imaging

PURPOSE

To retrospectively compare intraoperative ultrasonography (US) and preoperative magnetic resonance (MR) imaging with contrast material enhancement for the depiction of liver lesions in patients undergoing hepatic resection.

MATERIALS AND METHODS

A radiologist (D.V.S.) and a surgeon (K.K.T.) retrospectively identified 79 patients (36 female and 43 male patients; age range, 10-78 years; mean age, 57 years) who had undergone surgical resection for primary liver tumor or metastasis and had also undergone preoperative contrast-enhanced MR imaging within 6 weeks before surgery. MR imaging was performed with a 1.5-T system. Dedicated intraoperative US of the liver was performed or supervised by a gastrointestinal radiologist using a 7.5-MHz linear-array transducer, after adequate hepatic mobilization by the surgeon. Histopathologic evaluation of the 159 resected hepatic lesions served as the reference standard. The lesion distribution included colon cancer metastasis (n = 122), hepatocellular carcinoma (n = 23), cholangiocarcinoma (n = 6), cavernous hemangioma (n = 4), focal nodular hyperplasia (n = 2), hamartoma (n = 1), and metastatic embryonal sarcoma (n = 1).

RESULTS

Of 159 lesions, 138 (86.7%) were identified at both MR imaging and intraoperative US. Twelve additional lesions (7.5%) in 10 patients were detected only at intraoperative US (eight metastases, one hepatocellular carcinoma, one cholangiocarcinoma, one hemangioma, and one biliary hamartoma). Both modalities failed to depict nine lesions (5.6%) (four metastases, four hepatocellular carcinomas, and one cholangiocarcinoma). The sensitivities of MR imaging and intraoperative US for liver lesion depiction were 86.7% and 94.3%, respectively. Surgical management was altered on the basis of the intraoperative US findings in only three of 10 patients (4%).

CONCLUSION

Contrast-enhanced MR imaging is as sensitive as intraoperative US in depicting liver lesions before hepatic resection.

Modern hepatic imaging

This article provides a brief overview of the current status of commonly employed diagnostic techniques--US, CT, MR, and PET--for the evaluation of liver metastases and HCC as well as a description of imaging in RF ablation and liver transplantation. The various advantages and limitations of the techniques have been outlined. At the present time, at our center, MRI is used most often to evaluate these liver pathologies, due to its high accuracy for lesion detection and characterization.

Liver metastases in cancer: detection with contrast-enhanced ultrasonography

In patients with known or suspected malignancy, ultrasonography (US) is often the first choice for liver imaging because of its widespread availability and low cost. Compared with contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), the sensitivity of conventional US for detecting hepatic metastases is relatively poor. The advent of microbubble contrast agents changed this situation. Sensitivity and specificity increased substantially with the use of these contrast agents and contrast-specific imaging modes in recent years. Currently, numerous US imaging methods exist, based on Doppler techniques or harmonic imaging. They exploit the complex nonlinear behavior of microbubbles in a sound field to achieve marked augmentation of the US signal. Although microbubble contrast agents are essentially blood pool agents, some have a hepatosplenic specific late phase. Imaging during this late phase is particularly useful for improving the detection of malignant liver lesions and allows US to perform similarly to spiral CT as shown by recent studies. In addition, this late phase imaging is very helpful for lesion characterization. Low mechanical index imaging with the newer perfluor agents permits real-time imaging of the dynamic contrast behavior during the arterial, portal venous, and late phases and is particularly helpful for lesion characterization. The use of US for hemodynamic studies of the liver transit time may detect blood flow changes induced by micrometastases even before they become visible on imaging. In this field of functional imaging, further research is required to achieve conclusive results, which are not yet available.