Hepatic metastases: basic principles and implications for radiologists

Role of EUS in detection of liver metastasis not seen by computed tomography or magnetic resonance imaging during staging of pancreatic, gastrointestinal, and thoracic malignancies

Background and Objectives:

Liver metastases might not be detected by computed tomography (CT) and magnetic resonance imaging (MRI) due to their small size, but they can be detected by EUS. Furthermore, EUS-FNA has a significant impact on improving the diagnostic accuracy of EUS. The purpose of this study was to assess the feasibility of EUS in detection of occult small hepatic focal lesions at the time of primary tumor staging, not seen by CT or MRI.

Methods:

This prospective study included 730 patients who underwent EUS for staging or sampling of gastrointestinal, pancreatic, or thoracic malignancy. The liver was examined thoroughly for detection of occult lesions. CT or MRI was done within 1 week of EUS examination.

Results:

EUS examination of the liver detected focal lesions in 150 patients (20.5%) and metastases in 118 patients (16.2%); meanwhile, CT and MRI detected focal lesions in 99 patients (13.6%) and metastases in 82 patients (11.2%). EUS missed focal lesions in 7 patients, 6 of which were liver metastases (1.0% and 0.8%, respectively), while CT and MRI missed focal lesions in 58 patients, 42 of which were metastases (7.9% and 5.8%, respectively), which were detected by EUS.

Conclusion:

Thorough dedicated EUS examination of the liver is a feasible useful tool for detection of small hepatic lesions missed by CT and MRI. It is not considered an extra financial burden to the patient or health-care system because those patients are indicated for EUS examination for evaluation of their original lesion in the first place. Furthermore, EUS-FNA can add another advantage in diagnosing the etiology of such lesions.

Ultrasound Image-Based Radiomics: An Innovative Method to Identify Primary Tumorous Sources of Liver Metastases

OBJECTIVES

To develop radiomic models of B-mode ultrasound (US) signatures for determining the origin of primary tumors in metastatic liver disease.

METHODS

A total of 254 patients with a diagnosis of metastatic liver disease were included in this retrospective study. The patients were divided into 3 groups depending on the origin of the primary tumor: group 1 (digestive tract versus non-digestive tract tumors), group 2 (breast cancer versus non-breast cancer), and group 3 (lung cancer versus other malignancies). The patients in each group were allocated to a training or testing set (a ratio of 8:2). The region of interest of liver metastasis was determined through manual differentiation of the tumors, and radiomic signatures were acquired from B-mode US images. Optimal features were selected to develop 3 radiomic models using multiple-dimensionality reduction and classifier screening. The area under the curve (AUC) of the receiver operating characteristic curve was applied to assess each model's performance.

RESULTS

A total of 5936 features were extracted, and 40, 6, and 14 optimal features were sequentially identified for the development of radiomic models for groups 1, 2, and 3, respectively, with training set AUC values of 0.938, 0.974, and 0.768 and testing set AUC values of 0.767, 0.768, and 0.750. The differences in age, sex, and number of liver metastatic lesions varied greatly between the 4 primary tumors (P < .050).

CONCLUSIONS

B-mode US radiomic models could be effective supplemental means to identify the origin of hepatic metastatic lesions (ie, unknown primary sites).

Heterogeneity analysis of triphasic CT scan perfusion parameters in differential diagnosis of hepatocellular carcinoma and hemangioma

This study is to investigate quantitative measures and heterogeneity of perfusion parameters in the differential diagnosis of hepatocellular carcinoma (HCC) and hemangioma.In total, 32 HCC and 44 hemangioma (types 1, 2, and 3) cases were included in this retrospective study. Hepatic artery coefficient (HAC), portal vein coefficient (PVC), and arterial enhancement fraction (AEF) were calculated. Tumor heterogeneity was analyzed. Perfusion parameters and corresponding percentiles were compared between the HCC and hemangioma (especially atypical hemangioma) cases, as well as between the substantial lesion part and surrounding normal tissue.The mean value, and the 10th, 50th, 75th, and 90th percentiles of PVC were significantly lower in the HCC cases than the types 1 and 2 hemangioma cases (P < .01). Moreover, the 90th percentile PVC in the HCC cases was also significantly lower than the type 3 hemangioma case (P < .01), while the mean value, and all the percentiles of AEF in the HCC cases were higher than the types 2 and 3 hemangioma cases (P < .01). The 10th percentile HAC in the HCC cases was higher than the type 2 hemangioma cases (P < .05). The mean value, and the 10th and 50th percentile HAC in the HCC cases were higher than the type 3 hemangioma case (P < .05). However, there was no statistically significant difference in HAC between the HCC and type 1 hemangioma cases (P > .05).Quantitative measurement of perfusion parameters and heterogeneity analysis show significance differences in the early detection and differential diagnosis of HCC and hemangioma cases, which might contribute to increasing the diagnostic accuracy.

Arterial Phase with CAIPIRINHA-Dixon-TWIST (CDT)-Volume-Interpolated Breath-Hold Examination (VIBE) in Detecting Hepatic Metastases

PURPOSE: To evaluate lesion enhancement performance of Multi-Arterial CAIPIRINHA-Dixon-TWIST–Volume-Interpolated Breath-Hold Examination (MA-CDT-VIBE) for the detection of hepatic metastases. MATERIALS AND METHODS: Thirty-one patients with suspicious hepatic metastases were enrolled in this retrospective study. Two independent radiologists scored visualization of each lesion on a scale of 1 (poor visualization) to 11 (excellent visualization) on 11 sets of images. These included 6 hepatic arterial sub-phases acquired in one breath-hold, 1 series of the mean of 6 hepatic arterial sub-phases, 3 subtracted arterial sub-phases, and 1 portal venous phase. The phases with good (score 8–10) and excellent (score 11) lesion visualization were identified, and the number of lesions seen on each of these phases was compared to the number of lesions that was seen best on the equivalent-to-conventional single arterial phase as well as to those that were see best on the mean of 6 hepatic arterial sub-phases. Inter-reader agreement was also calculated. RESULTS: The MA-CDT-VIBE was successfully acquired in 25 patients with hypervascular metastases (96 lesions) and 6 patients with hypovascular metastases (13 lesions). In case of hypervascular metastases, the 6th/6 arterial sub-phase had excellent lesion visualization (sore of 11) in 56 and 44 lesions for the 2 readers, respectively. Good lesion visualization (score of 8-10) was recorded in 5th/6 arterial subphases, in 81 and 67 lesions for the 2 readers, respectively. In case of hypovascular metastases, the portal venous phase had excellent lesion visualization (sore of 11) in all 13 lesions for the 2 readers. Good lesion visualization (score of 8–10) was recorded in 12 and 13 lesions on the 5th/6 and 6th/6 arterial subphases, respectively. More hypervascular lesions scored good (score of 8–10) and excellent (score of 11) on the 5th/6 and 6th/6 phases of MA-CDT-VIBE compared with the equivalent-to-conventional single arterial phase (3rd/6) and the set with mean of 6 hepatic arterial sub-phases. The results were statistically significant (t test, P < .0001). Inter-reader agreement was good for hypervascular lesions (kappa = 0.627, P < .0001) and excellent for hypovascular lesions (kappa = 1.0, P < .0001), respectively. CONCLUSIONS: The MA-CDT-VIBE improves lesion conspicuity by providing a wide observation window for hypervascular lesions. For hypovascular lesions, the advantage of multiple arterial sub-phases over the portal venous phase is not apparent.

MRI characteristics for the differential diagnosis of benign and malignant small solitary hypovascular hepatic nodules

PURPOSE

To compare the MRI findings of benign and malignant solitary hypovascular hepatic nodules and identify the differentiating features.

MATERIALS AND METHODS

A total of 135 patients with solitary hypovascular hepatic lesions up to 3 cm (mass forming intrahepatic cholangiocarcinoma, n=29; metastases, n=26; inflammatory pseudotumors and solitary necrotic nodule, n=48; and hemangioma, n=32) were assessed. MRI findings were analyzed, and lesions were scored for peripheral and intratumoral appearance and enhancement patterns.

RESULTS

Univariate and multivariate analyses showed that the most common findings for benign lesions were subcapsular, sharp margin, homogeneous, marked high signal on T2WI, mild hyperintensity on T2WI, increasing intensity of peripheral globular enhancement, and persistent central septum-like linear enhancement on delayed phase (P<0.05). An area under the curve of 0.955 was obtained for differentiating malignant from benign nodules using the combined imaging features of ill-defined margins, heterogeneity, decreasing intensity of peripheral rim-like enhancement, and central increasing intensity of patchy enhancement. Interobserver agreement was good, ranging from 0.72 to 1.00.

CONCLUSION

MRI may be a useful noninvasive method for determining whether hypovascular hepatic nodules are malignant or benign.

EUS-derived criteria for distinguishing benign from malignant metastatic solid hepatic masses

BACKGROUND

Detection of hepatic metastases during EUS is an important component of tumor staging.

OBJECTIVE

To describe our experience with EUS-guided FNA (EUS-FNA) of solid hepatic masses and derive and validate criteria to help distinguish between benign and malignant hepatic masses.

DESIGN

Retrospective study, survey.

SETTING

Single, tertiary-care referral center.

PATIENTS

Medical records were reviewed for all patients undergoing EUS-FNA of solid hepatic masses over a 12-year period.

INTERVENTIONS

EUS-FNA of solid hepatic masses.

MAIN OUTCOME MEASUREMENTS

Masses were deemed benign or malignant according to predetermined criteria. EUS images from 200 patients were used to create derivation and validation cohorts of 100 cases each, matched by cytopathologic diagnosis. Ten expert endosonographers blindly rated 15 initial endosonographic features of each of the 100 images in the derivation cohort. These data were used to derive an EUS scoring system that was then validated by using the validation cohort by the expert endosonographer with the highest diagnostic accuracy.

RESULTS

A total of 332 patients underwent EUS-FNA of a hepatic mass. Interobserver agreement regarding the initial endosonographic features among the expert endosonographers was fair to moderate, with a mean diagnostic accuracy of 73% (standard deviation 5.6). A scoring system incorporating 7 EUS features was developed to distinguish benign from malignant hepatic masses by using the derivation cohort with an area under the receiver operating curve (AUC) of 0.92; when applied to the validation cohort, performance was similar (AUC 0.86). The combined positive predictive value of both cohorts was 88%.

LIMITATIONS

Single center, retrospective, only one expert endosonographer deriving and validating the EUS criteria.

CONCLUSION

An EUS scoring system was developed that helps distinguish benign from malignant hepatic masses. Further study is required to determine the impact of these EUS criteria among endosonographers of all experience.

Focal liver lesions detection and characterization: The advantages of gadoxetic acid-enhanced liver MRI

Since its clinical introduction, several studies in literature have investigated gadolinium ethoxybenzhyl diethylenetriaminepentaacetic acid or gadoxetic acid (Gd-EOB-DTPA) properties. Following contrast injection, it provides dynamic vascular phases (arterial, portal and equilibrium phases) and hepatobiliary phase, the latter due to its uptake by functional hepatocytes. The main advantages of Gd-EOB-DTPA of focal liver lesion detection and characterization are discussed in this paper. Namely, we focus on the possibility of distinguishing focal nodular hyperplasia (FNH) from hepatic adenoma (HA), the identification of early hepatocellular carcinoma (HCC) and the pre-operative assessment of metastasis in liver parenchyma. Regarding the differentiation between FNH and HA, adenoma typically appears hypointense in hepatobiliary phase, whereas FNH is isointense or hyperintense to the surrounding hepatic parenchyma. As for the identification of early HCCs, many papers recently published in literature have emphasized the contribution of hepatobiliary phase in the characterization of nodules without a typical hallmark of HCC. Atypical nodules (no hypervascularizaton observed on arterial phase and/or no hypovascular appearance on portal phase) with low signal intensity in the hepatobiliary phase, have a high probability of malignancy. Finally, regarding the evaluation of focal hepatic metastases, magnetic resonance pre-operative assessment using gadoxetic acid allows for more accurate diagnosis.

Review article: the biology, diagnosis and management of gastrointestinal stromal tumours

BACKGROUND

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumours of the gastrointestinal tract with an increasing incidence.

AIMS

To review the biology, diagnosis and treatment of gastrointestinal stromal tumours.

METHODS

A PubMed search using the phrases 'Gastrointestinal stromal tumor', 'imatinib', 'c-kit'.

RESULTS

The diagnosis of GIST is established by histology supplemented by the immunohistochemical marker CD117, which is positive in 95% of cases. The most common site of the tumour is the stomach. Most GIST are benign with 20-30% malignant. Five-year survival for malignant GIST ranges between 35% and 65% and depends primarily on tumour size, mitotic index and location. The malignant behaviour of GIST is best assessed by invasion of adjacent structures and distant metastases. The gold standard for treatment is surgical resection. Imatinib, a tyrosine kinase inhibitor, is the primary therapy for unresectable, recurrent or metastatic disease.

CONCLUSIONS

Gastrointestinal stromal tumours are rare tumours of the gastrointestinal tract and they vary in presentation. When surgical resection is not achievable, imatinib is the treatment of choice.

Current role of transarterial chemoembolization and radioembolization in the treatment of metastatic colorectal cancer

In this article, we review two liver-directed therapies that are currently used for the palliative treatment of primary and secondary hepatic malignancies, transcatheter arterial chemoembolization (TACE), including a new type of TACE with drug-eluting beads, and radioembolization. Important developments and administration techniques for all therapies are discussed, as well as their integration into the current routine clinical care for management of metastatic colorectal cancer. According to published data from clinical trials, as presented in this review, both radioembolization and TACE/TACE with drug-eluting beads have been proven to be safe and effective in selected patients with chemorefractory liver metastases from colorectal cancer. For patients with unresectable liver-only or liver-dominant disease who have failed standard chemotherapy options or for whom chemotherapy is contraindicated, new modalities, such as those discussed, are particularly valid and promising if clinical guidelines for patient selection and treatment administration are followed.

Comparative accuracy of intravenous contrast-enhanced CT versus noncontrast CT plus intravenous contrast-enhanced CT in the detection and characterization of patients with hypervascular liver metastases: a critically appraised topic

RATIONAL AND OBJECTIVES

To evaluate whether addition of nonenhanced computed tomography (NECT) to intravenous contrast-enhanced (CE) abdominal CT improves detection or characterization of hypervascular liver masses. Patients were referred for initial staging or follow-up with known breast, melanoma, neuroendocrine, or thyroid cancer.

MATERIAL AND METHODS

The literature was searched using the patient, intervention, comparison, and outcome (PICO) method. Retrieved articles were critically appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-based Medicine hierarchy of validity for diagnostic studies.

RESULTS

One thousand one hundred studies were reviewed; only 11 studies matched the PICO of our study and were appraised. Most of the appraised articles were published in the 1990s using older technology and contrast delivery. The retrieved diagnostic performance for characterization of liver metastases showed sensitivity/specificity of 97%/76% for NECT, 97%/75% for arterial CT, and 98%/76% for portal venous phase CT in patients with breast cancer; sensitivity of 96% (arterial and portal CT) versus 100% (NECT, arterial and portal CT) in patients with melanoma; and sensitivity of 43% (portal CT) versus 17% (NECT) in patients with neuroendocrine tumor. No primary study was found for performance of different CT protocols in patients with thyroid cancer. Available evidence showed radiologists reported more conspicuous liver masses on CECT compared to NECT in patients with breast or neuroendocrine cancer.

CONCLUSIONS

Based on existing evidence, NECT only adds a small incremental value to CECT for detection/characterization of hypervascular liver metastases. Addition of NECT increases patient's exposure to radiation and the number of images available for interpretation.

MR imaging in patients with suspected liver metastases: value of liver-specific contrast agent gadoxetic acid

Objective

To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance (MR) imaging with that of triple-phase multidetector-row computed tomography (MDCT) in the detection of liver metastasis.

Materials and Methods

Our institutional review board approved this retrospective study and waived informed consent. The study population consisted of 51 patients with hepatic metastases and 62 patients with benign hepatic lesions, who underwent triple-phase MDCT and gadoxetic acid-enhanced MRI within one month. Two radiologists independently and randomly reviewed MDCT and MRI images regarding the presence and probability of liver metastasis. In order to determine additional value of hepatobiliary-phase (HBP), the dynamic-MRI set alone and combined dynamic-and-HBP set were evaluated, respectively. The standard of reference was a combination of pathology diagnosis and follow-up imaging. For each reader, diagnostic accuracy was compared using the jackknife alternative free-response receiver-operating-characteristic (JAFROC).

Results

For both readers, average JAFROC figure-of-merit (FOM) was significantly higher on the MR image sets than on the MDCT images: average FOM was 0.582 on the MDCT, 0.788 on the dynamic-MRI set and 0.847 on the combined HBP set, respectively (p < 0.0001). The differences were more prominent for small (≤ 1 cm) lesions: average FOM values were 0.433 on MDCT, 0.711 on the dynamic-MRI set and 0.828 on the combined HBP set, respectively (p < 0.0001). Sensitivity increased significantly with the addition of HBP in gadoxetic acid-enhanced MR imaging (p < 0.0001).

Conclusion

Gadoxetic acid-enhanced MRI shows a better performance than triple-phase MDCT for the detection of hepatic metastasis, especially for small (≤ 1 cm) lesions.

Transarterial chemoembolization of unresectable systemic chemotherapy-refractory liver metastases from colorectal cancer: long-term results over a 10-year period

The aims of the study were to evaluate therapeutic efficacy and to determine the prognostic factors for treatment success in patients with liver metastases from colorectal cancer (CRC) treated with transarterial chemoembolization (TACE). A total of 564 patients (mean age, 60.3 years) with liver metastases of CRC were repeatedly treated with TACE. In total, 3,384 TACE procedures were performed (mean, six sessions per patient). The local chemotherapy protocol consisted of mitomycin C alone (43.1%), mitomycin C with gemcitabine (27.1%), mitomycin C with irinotecan (15.6%) or mitomycin C with irinotecan and cisplatin (15.6%). Embolization was performed with lipiodol and starch microspheres. Tumor response was evaluated using magnetic resonance imaging or computed tomography. The change in tumor size was calculated and the response was evaluated according to the RECIST-Criteria. Survival rates were calculated according to the Kaplan-Meier method. Prognostic factors for patient's survival were evaluated using log-rank test. Evaluation of local tumor control showed partial response in 16.7%, stable disease in 48.2% and progressive disease in 16.7%. The 1-year survival rate after chemoembolization was 62%, the 2-year survival rate was 28% and the 3-year survival rate was 7%. Median survival from the start of chemoembolization treatment was 14.3 months. The indication (p = 0.001) and initial tumor response (p = 0.015) were statistically significant factors for patient's survival. TACE is a minimally invasive therapy option for controlling local metastases and improving survival time in patients with hepatic metastases from CRC. TN stage, extrahepatic metastases, number of lesions, tumor location within the liver and choice of chemotherapy protocol of TACE are none significant factors for patient's survival.

Role of contrast enhanced ultrasound in radiofrequency ablation of metastatic liver carcinoma

OBJECTIVE

To investigate the application of contrast enhanced ultrasound (CEUS) in planning and guiding for radiofrequency ablation (RFA) for metastatic liver carcinoma (MLC).

METHODS

One hundred and thirty-five patients with clinically and pathologically diagnosed MLC (from gastrointestinal tumors) were included in the present study, and 104 of them had received CEUS prior to RFA to assess the number, size, shape, infiltration, location and enhancing features of the lesions. Among the 104 patients, 21 (20.1%) were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS. The remaining 83 patients with 147 lesions underwent RFA (group A). During the same period, other 31 patients with 102 lesions serving as control group were treated based on findings of conventional ultrasound without contrast (group B). The patients underwent follow-up enhanced CT at the 1st month, and then every 3-6 months after RFA. The tumor was considered as early necrosis if no contrast enhancement was detected in the treated area on the CT scan at the 1st month.

RESULTS

In group A, 72 of 147 MLC lesions (48.9%) showed increased sizes on CEUS. Among them, 48 lesions (66.6%) appeared enlarged in arterial phase, and 24 (33.3%) showed enlarged hypoechoic area in parenchymal phase. CEUS showed total 61 additional lesions in 35 patients (42.1%) (ranged from 8 to 15 mm) compared with conventional ultrasound (US), and 42 (68.8%) of them were visualized in parenchymal phase only. There were total 208 lesions in group A underwent RFA with CEUS planning, and the tumor necrosis rate was 94.2% (196/208). In this group, local recurrence was found in 16 lesions (7.7%) during 3-42 months' following up, and new metastases were seen in 30 cases (36.1%). For group B, the tumor necrosis rate was 86.3% (88/102), local recurrence in 17 lesions (16.7%), and new metastases in 13 cases (41.9%). Tumor early necrosis and recurrence rates were significantly different between the two groups (P=0.018, P=0.016, respectively).

CONCLUSION

CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment.

That liver lesion on MDCT in the oncology patient: is it important?

Multidetector-row computed tomography (MDCT) has become the primary imaging test for the staging and follow-up of most malignancies that originate outside of the central nervous system. Technical advances in this imaging technique have led to significant improvement in the detection of metastatic disease to the liver. An unintended by-product of this improving diagnostic acumen is the discovery of incidental hepatic lesions in oncology patients that in the past remained undetected. These ubiquitous, incidentally identified hepatic lesions have created a management dilemma for both clinicians and radiologists: are these lesions benign or do they represent metastases? Naturally, the answer to this question has profound prognostic and therapeutic implications. In this review, guidelines concerning the diagnosis and management of some of the more common hepatic incidental lesions detected in patients with extrahepatic malignancies are presented.

Gadoxetic acid-enhanced 3.0T MRI for the evaluation of hepatic metastasis from colorectal cancer: metastasis is not always seen as a "defect" on the hepatobiliary phase

PURPOSE

To determine specific imaging features of hepatic metastasis from colorectal cancer, focusing on the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI.

MATERIALS AND METHODS

Over a 2-year period, 79 hepatic metastatic lesions were identified from 32 patients (22 men and 10 women) who proven colorectal cancer and underwent gadoxetic acid-enhanced 3.0T MRI. Hepatic metastases were proven pathologically in 16 patients: by surgical liver resection (n=14) and by US-guided biopsy (n=2). The remaining 16 patients were considered to have hepatic metastasis based on imaging studies and clinical information. Two radiologists evaluated the imaging features of each MRI sequence, including high resolution T2WI, dynamic contrast enhancement study with hepatobiliary phase, and diffusion weighted image. We also compared SI of the lesions on T2WI and HBP.

RESULTS

T2WI showed homogeneous high SI (n=25; 31.7%), target appearance (n=3; 3.8%), reversed target appearance (n=2; 2.6%), and heterogeneously high SI (n=49; 62%). On HBP, homogeneous defect were seen in 22 lesions (27.9%), target appearance in five lesions (6.4%), reversed target appearance in two lesions (2.5%), and heterogeneous defect in 50 lesions (63.3%); including reticular (70%), partially globular (26%), and diffuse GGO-like (4%) patterns. According to the imaging features on HBP, the homogeneous defect and heterogeneous defect groups had a mean ADC value of 0.99 × 10(-3) and 1.07 × 10(-3)mm(2)/s, respectively, without statistically significant difference.

CONCLUSION

Hepatic metastasis from colorectal cancer usually showed as a heterogeneous defect on HBP and a heterogeneous high SI on T2WI. The generally accepted "true defect" was not a common finding in hepatic metastasis from colorectal cancer.

Radiological features of metastatic gastrointestinal stromal tumors

The imaging features of 42 histopathologically confirmed cases of Gastrointestinal Stromal Tumors (GIST) were analyzed, to observe the pattern of metastasis. At presentation 22 of 42 patients (52.3%) showed metastasis. During follow-up, three more cases developed metastasis, within one year of resection. Mesentery, omentum, and liver were the most frequent sites for metastasis. Other sites that were rarely reported to be involved were increasingly recognized to show metastasis due to longer survival. The metastasis often showed attenuation and enhancement characteristics, similar to primary GIST, and frequently showed necrosis, hemorrhage, and calcification.

Tumor and non-tumor liver angiogenesis is traced and evaluated by hepatic arterial ultrasound in murine models

We studied the relationships between hepatic and mesenteric mean blood-flow velocities (mBFVs) measured by ultrasound imaging and (1) downstream tumor angiogenesis during liver metastasis induced by spleen injection of LS174 human colon cells overexpressing the antiangiogenic Netrin4 (LS174-NT4) or not (LS174-WT) and (2) downstream normal angiogenesis during hepatic regeneration after 50% hepatectomy. Liver volume and mBFVs were measured before and after surgery, at day 30 in the first model and at days 2, 7 and 16 in the second model. LS174-NT-4 vs. LS174-WT mice presented fewer metastases (25% vs. 90%, p < 0.001) and decreased hepatic mBFVs (16.5 ± 0.8 vs. 21.8 ± 1.4 cm s(-1), p < 0.01), without difference in mesenteric mBFVs. After partial hepatectomy, hepatic and mesenteric mBFVs increased at day 7, from 12.4 ± 1.7 and 11.8 ± 2.6 to 19.1 ± 1.8 and 17.5 ± 2.4 cm s(-1), respectively, (p < 0.01) then returned to baseline as liver volume. Duplex Doppler ultrasonography reliably assesses normal or tumor angiogenesis and may provide follow-up functional evaluation.

Imaging diagnosis 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 diagnosis colorectal liver metastases. It is well established that hepatic resection improves the long-term prognosis of many patients with liver metastases. However, incomplete resection does not prolong survival, so knowledge of the exact extent of intra-hepatic disease is crucially important in determining patient management and outcome. The diagnosis of liver metastases relies first and totally on imaging to decide which patients may be surgical candidates. This review will discuss the imaging options and their appropriate indications. Imaging and evaluating of colorectal liver metastases (CRLM) have been performed with contrast-enhanced ultrasound, multi-detector computed tomography, magnetic resonance imaging (MRI) with extra-cellular contrast media and liver-specific contrast media MRI, and positron emission tomography/computed tomography. This review will concentrate on the imaging approach of CRLM, and also discuss certain characteristics of some liver lesions. We aim to highlight the advantages of each imaging technique, as well as underscoring potential pitfalls and limitations.

Standardisation of liver MDCT by tracking liver parenchyma enhancement to trigger imaging

OBJECTIVE

To assess parenchymal bolus-triggering in terms of liver enhancement, lesion-to-liver conspicuity and inter-image variability across serial follow-up MDCTs.

METHODS

We reviewed MDCTs of 50 patients with hepatic metastases who had a baseline CT and two follow-up examinations. In 25 consecutive patients CT data acquisition was initiated by liver parenchyma triggering at a 50-HU enhancement threshold. In a matched control group, imaging was performed with an empirical delay of 65 s. CT attenuation values were assessed in vessels, liver parenchyma and metastasis. Target lesions were classified according to five enhancement patterns.

RESULTS

Compared with the control group, liver enhancement was significantly higher with parenchyma triggering (59.8 ± 7.6 HU vs. 48.8 ± 11.2 HU, P = 0.0002). The same was true for conspicuity (liver parenchyma - lesion attenuation) of hypo-enhancing lesions (72.2 ± 15.9 HU vs. 52.7 ± 19.4 HU, P = 0.0006). Liver triggering was associated with reduced variability for liver enhancement among different patients (P = 0.035) and across serial follow-up examinations in individual patients (P < 0.0001). The number of patients presenting with uniform lesion enhancement pattern across serial examinations was significantly higher in the triggered group (20 vs. 11; P = 0.018).

CONCLUSION

Liver parenchyma triggering provides superior lesion conspicuity and improves standardisation of image quality across follow-up examinations with greater uniformity of enhancement patterns.

KEY POINTS

Liver parenchyma tracking improves liver enhancement and lesion-to-liver conspicuity in abdominal CT. In serial CT studies this technique reduces variability of conspicuity and enhancement patterns. Higher liver-to-lesion conspicuity is a prerequisite for reliable detection of liver lesions. Stabilisation of enhancement permits more accurate follow-up of oncology patients.

Percutaneous radiofrequency ablation using internally cooled wet electrodes for treatment of colorectal liver metastases

AIM

To evaluate the efficacy and safety of internally cooled wet (ICW) electrodes, which provide interstitial infusion of saline and intra-electrode cooling simultaneously, in the percutaneous radiofrequency ablation (RFA) of liver metastases from colorectal cancer.

MATERIALS AND METHODS

From February 2008 to October 2010, 27 patients with 35 hepatic metastatic lesions (mean size 1.99cm; range 0.7-3.8cm) underwent RFA using ICW electrodes. Of these 35 tumours, 32 had diameters ≤3cm, and three had diameters of 3-4cm. Moreover, 18 tumours were non-subcapsular and 17 were subcapsular.

RESULTS

No patients (0%) had major complications after RFA. During follow-up (median 27 months; range 4.5-36 months), 14 of the 35 treated lesions (40%) showed local tumour progression. The local tumour progression-free survival rates at 1 and 3 years were 73 and 56%, respectively. The local tumour progression-free survival period was significantly longer in patients with tumours ≤2cm than >2cm (p<0.001), but did not differ significantly between patients with non-subcapsular and subcapsular tumours (p=0.454). The overall 1 and 3 year survival rates after RFA were 100 and 77%, respectively.

CONCLUSIONS

Percutaneous RFA using ICW electrodes is safe and technically feasible for the treatment of liver metastases from colorectal cancer. It provides effective local tumour control with low complication rates and reduced number of needle placements.

Volumetric arterial enhancement fraction predicts tumor recurrence after hepatic radiofrequency ablation of liver metastases: initial results

OBJECTIVE

The objective of our study was to investigate the diagnostic value of the volumetric arterial enhancement fraction of the liver with color mapping for the early detection of tumor relapse after hepatic radiofrequency ablation (RFA).

MATERIALS AND METHODS

Fifty-three patients (24 men, 29 women; mean age ± SD, 65 ± 10 years) with a total of 215 liver metastases treated by RFA and a mean postinterventional follow-up period of 20 ± 15 (SD) months were included in this retrospective study. Quantitative arterial enhancement fraction color maps of the whole liver were computed from triple-phase contrast-enhanced MDCT images. Follow-up examinations served as the standard of reference. The diagnostic performance of the arterial enhancement fraction color maps to predict subsequent tumor occurrence before tumor was visible on routine multiphase CT images was evaluated.

RESULTS

The mean arterial enhancement fraction of segments that developed metastases (62% ± 23%) was significantly higher than the mean of segments that did not develop metastases (39% ± 20%) (p < 0.0001). Receiver operating characteristic curve analysis revealed a probability of 77% for arterial enhancement fraction values to be higher in case of subsequent metastases as compared with liver parenchyma without tumor recurrence.

CONCLUSION

The arterial enhancement fraction provides incremental value in the imaging surveillance for liver metastases after RFA. Arterial enhancement fraction color maps may be suited to predict tumor recurrence earlier than routine assessment using contrast-enhanced MDCT.

Diffusion-weighted MRI and liver metastases

Liver metastases are the most frequently encountered malignant liver lesions in the Western countries. Accurate diagnosis of liver metastases is essential for appropriate management of these patients. Multiple imaging modalities, including ultrasound, CT, positron emission tomography, and MRI, are available for the evaluation of patients with suspected or known liver metastases. Contrast-enhanced MRI has a high accuracy for detection and characterization of liver lesions. Additionally, diffusion-weighted MRI (DWI) has been gaining increasing attention. It is a noncontrast technique that is easy to perform, could be incorporated in routine clinical protocols, and has the potential to provide tissue characterization. This article discusses the basic principles of DWI and discusses its emerging role in the detection of liver metastases in patients with extrahepatic malignancies.

Vascular profile characterization of liver tumors by magnetic resonance imaging using hemodynamic response imaging in mice

Recently, we have demonstrated the feasibility of using hemodynamic response imaging (HRI), a functional magnetic resonance imaging (MRI) method combined with hypercapnia and hyperoxia, for monitoring vascular changes during liver pathologies without the need of contrast material. In this study, we evaluated HRI ability to assess changes in liver tumor vasculature during tumor establishment, progression, and antiangiogenic therapy. Colorectal adenocarcinoma cells were injected intrasplenically to model colorectal liver metastasis (CRLM) and the Mdr2 knockout mice were used to model primary hepatic tumors. Hepatic perfusion parameters were evaluated using the HRI protocol and were compared with contrast-enhanced (CE) MRI. The hypovascularity and the increased arterial blood supply in well-defined CRLM were demonstrated by HRI. In CRLM-bearing mice, the entire liver perfusion was attenuated as the HRI maps were significantly reduced by 35%. This study demonstrates that the HRI method showed enhanced sensitivity for small CRLM (1-2 mm) detection compared with CE-MRI (82% versus 38%, respectively). In addition, HRI could demonstrate the vasculature alteration during CRLM progression (arborized vessels), which was further confirmed by histology. Moreover, HRI revealed the vascular changes induced by rapamycin treatment. Finally, HRI facilitates primary hepatic tumor characterization with good correlation to the pathologic differentiation. The HRI method is highly sensitive to subtle hemodynamic changes induced by CRLM and, hence, can function as an imaging tool for understanding the hemodynamic changes occurring during CRLM establishment, progression, and antiangiogenic treatment. In addition, this method facilitated the differentiation between different types of hepatic lesions based on their vascular profile noninvasively.

Improved characterization of focal liver lesions with liver-specific gadoxetic acid disodium-enhanced magnetic resonance imaging: a multicenter phase 3 clinical trial

OBJECTIVES

To evaluate the safety of gadoxetic acid disodium (Gd-EOB-DTPA) magnetic resonance imaging (MRI) and its efficacy in characterizing liver lesions.

METHODS

Lesion characterization and classification using combined (unenhanced and Gd-EOB-DTPA-enhanced) MRI were compared with those using unenhanced MRI and contrast-enhanced spiral computed tomography (CT) using on-site clinical and off-site blinded evaluations for patients with focal liver lesions.

RESULTS

Gadoxetic acid disodium was well tolerated in this study. For the clinical evaluation, more lesions were correctly characterized using combined (unenhanced and Gd-EOB-DTPA-enhanced) MRI than using unenhanced MRI and spiral CT (96% vs 84% and 85%, respectively; P < or = 0.0008). For the blinded evaluation, more lesions were correctly characterized using combined MRI compared with using unenhanced MRI (61%-76% vs 48%-65%, respectively; P < or = 0.0012 for 2/3 readers); when compared with spiral CT, a similar proportion of lesions were correctly characterized.

CONCLUSIONS

Gadoxetic acid disodium-enhanced MRI is of clinical benefit relative to unenhanced MRI and spiral CT for a radiological diagnosis of liver lesions.

Small colorectal liver metastases: detection with SPIO-enhanced MRI in comparison with gadobenate dimeglumine-enhanced MRI and CT imaging

The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs separately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.

Repeated transarterial chemoembolization in the treatment of liver metastases of colorectal cancer: prospective study

PURPOSE

To evaluate local tumor control and survival data after transarterial chemoembolization with different drug combinations in the palliative treatment of liver metastases in patients with colorectal cancer.

MATERIALS AND METHODS

The study was approved by institutional review board, and informed consent was obtained from all patients included in the study. A total of 463 patients (mean age, 62.5 years; range, 34.7-88.1 years) with unresectable liver metastases of colorectal cancer that did not respond to systemic chemotherapy were repeatedly treated with chemoembolization in 4-week intervals. In total, 2441 chemoembolization procedures were performed (mean, 5.3 sessions per patient). Of 463 patients, 67.4% had multiple (five or more) metastases, 8% had one metastasis, 10.4% had two metastases, and 14.3% had three or four metastases. The local chemotherapy protocol consisted of mitomycin C alone (n = 243), mitomycin C with gemcitabine (n = 153), or mitomycin C with irinotecan (n = 67). Embolization was performed with lipiodol and starch microspheres for vessel occlusion. Tumor response was evaluated with magnetic resonance imaging. The change in tumor size was calculated and the response was evaluated according to the Response Evaluation Criteria in Solid Tumors. Survival rates from first diagnosis and from first chemoembolization session were calculated according to the Kaplan-Meier method. Follow-up imaging was performed until patient death.

RESULTS

Evaluation of local tumor control resulted in partial response (68 patients [14.7%]), stable disease (223 patients [48.2%]), and progressive disease (172 patients [37.1%]). The 1-year survival rate after chemoembolization was 62%, and the 2-year survival rate was 28%. Median survival from date of diagnosis of liver metastases was 38 months and from the start of chemoembolization treatment was 14 months. There was no statistically significant difference between the three treatment protocols.

CONCLUSION

Chemoembolization is a minimally invasive therapy option for palliative treatment of liver metastases in patients with colorectal cancer, with similar results among three chemoembolization protocols.

[Metastases of colorectal carcinoma]

Metastases of colorectal cancer represent an interdisciplinary therapeutic challenge. Evidence-based guidelines are supportive of treatment decisions in specific situations with the objective to improve the therapeutic outcome for patients. Interventional tumor therapies are increasingly applied therapeutic options in the treatment of colorectal metastases. The current literature indicates that thermoablation of colorectal liver metastasis can lead to an improved survival in selected patients. However, recommendation of thermoablation as a part of guidelines for the therapy of colorectal metastases is restricted due to a shortcoming of randomized controlled trials. Therefore, interventional tumor therapies have to be evaluated in comparison with standard therapies, particularly with regard to surgical resection and chemotherapy. Moreover, the interdisciplinary combination of tumor ablation, surgical resection, and chemotherapy is a promising approach for the optimization of oncological therapy strategies in the treatment of colorectal metastases.

Liver metastases from colorectal cancer: imaging with superparamagnetic iron oxide (SPIO)-enhanced MR imaging, computed tomography and positron emission tomography

The literature about superparamagnetic iron oxide-enhanced MR imaging, computed tomography (CT) and PET (positron emission tomography using fluorine-18 labelled fluoro-deoxy-glucose) in detection of liver metastases (LM) from colorectal cancer is reviewed in this update. Special emphasis is given to studies with surgical standard of reference allowing for the lesion-by-lesion sensitivity to be determined. Based on the review, it is concluded that state-of-the-art anatomical imaging, e.g., SPIO-enhanced MR imaging and multidetector CT (MDCT), must be considered more sensitive than PET in detection of individual LM, due to technical developments in MR imaging, such as liver specific contrast agents, modern sequences and high performance gradients, and in modern MDCT have increased the performance of these modalities. MR imaging with a liver specific contrast agent is recommended for the preoperative evaluation before liver surgery for LM because of high sensitivity and better discrimination between small LM and cysts compared to MDCT. PET or PET/CT can be used for detection of extra-hepatic tumor before liver surgery.

Imaging to optimally stage lung cancer: conventional modalities and PET/CT

Accurately staging patients with lung cancer is important in determining treatment options and prognoses. Staging allows the distinction of patients who are candidates for surgical resection from those with inoperable disease who may be treated with chemotherapy and/or radiation therapy. Conventional imaging plays an essential role in the noninvasive and invasive methods of the evaluation and staging of patients with non-small-cell lung cancer (NSCLC). Imaging modalities used for staging include chest radiography, chest computed tomography (CT), abdominal CT, brain CT or magnetic resonance imaging, bone scans, and (18)F-2-deoxy-d-glucose positron emission tomography (PET). Recently, PET/CT, the integration of the functional data of PET with the anatomic data of CT, has emerged as a modality to potentially change the way patients are evaluated. This article reviews current recommendations regarding the staging of patients with NSCLC and addresses the role of PET/CT.

Changes of Intratumoral Microvessels and Blood Perfusion during Establishment of Hepatic Metastases in Mice

PURPOSE

To prospectively evaluate the stepwise changes that occur in intratumoral microvessels and microcirculation during the establishment of murine colonic hepatic metastases by using in vivo fluorescent microscopy and to compare the changes with tumor angiogenesis evaluated with an immunohistochemical study.

MATERIALS AND METHODS

This study was approved by the institutional animal care and use committee. Twenty-five mice with hepatic metastases created with injection of murine colonic adenocarcinoma (colon 26) tumor cells into the spleen were examined with in vivo microscopy and immunohistochemical study for CD34, intracellular adhesion molecule (ICAM-1), and alpha smooth muscle actin (alpha-SMA). The tumor size, microcirculation in tumors, intratumoral microvessel density (MVD), afferent MVD, and CD34-positive MVD were evaluated. The data among the tumors that showed different hemodynamic or immunohistochemical patterns were compared with the Kruskal-Wallis test and the Student t test.

RESULTS

Four stepwise patterns were observed according to the changes in morphology, hemodynamics, and immunohistochemical characteristics of intratumoral microvessels during the establishment of hepatic metastases, as follows: metastases without definite intratumoral blood perfusion or any intratumoral microvessels (mean diameter, approximately 180 microm), metastases with portal perfusion and intratumoral ICAM-1-positive residual hepatic sinusoids (mean diameter, approximately 290 microm), metastases with mixed portal and arterial perfusion and increased CD34-positive microvessels and alpha-SMA-positive arterioles (mean diameter, approximately 520 microm), and metastases with exclusively arterial perfusion and increased CD34-positive microvessels and alpha-SMA-positive arterioles (mean diameter, >2000 microm). The differences among the mean sizes of the tumors that showed these four patterns were statistically significant (P < .01).

CONCLUSION

Stepwise changes of intratumoral microcirculation were revealed from direct diffusion, to portal perfusion, to mixed portal and arterial perfusion, and finally to arterial perfusion in accordance with stepwise tumor neovascularization during the growth of murine colonic hepatic metastases.

Metastatic carcinoma of the breast: the appearances of metastatic spread to the abdomen and pelvis as demonstrated by CT

This review illustrates some CT appearances of metastatic breast cancer in the subdiaphragmatic abdomen and pelvis. Such manifestations are not uncommon in advanced disease and familiarity will enable confident diagnosis in patients at risk for metastatic disease.

Actual role of radiofrequency ablation of liver metastases

The liver is, second only to lymph nodes, the most common site for metastatic disease irrespective of the primary tumour. More than 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improved survival in patients with colorectal metastases, only approximately 20% of patients are eligible for surgery. Thermal ablation and especially radiofrequency ablation emerge as an important additional therapy modality for the treatment of liver metastases. RF ablation shows a benefit in life expectancy and may lead in a selected patient group to cure. Percutaneous RF ablation appears safer (versus cryotherapy), easier (versus laser), and more effective (versus ethanol instillation and transarterial chemoembolisation) compared with other minimally invasive procedures. RF ablation can be performed by a percutaneous, laparoscopical or laparotomic approach, and may be potentially combined with chemotherapy and surgery. At present ideal candidates have tumours with a maximum diameter less than 3.5 cm. An untreatable primary tumour or a systemic disease represents contraindications for performing local therapies. Permanent technical improvements of thermal ablation devices and a better integration of thermal ablation in the overall patient care may lead to prognosis improvement in patients with liver metastases.

Evaluation of a Novel Time-Efficient Protocol for Gadobenate Dimeglumine (Gd-BOPTA)-Enhanced Liver Magnetic Resonance Imaging

OBJECTIVE

We sought to evaluate gadobenate dimeglumine for the detection and characterization of focal liver lesions in the unenhanced and already pre-enhanced liver.

MATERIALS AND METHODS

Sixty patients were evaluated prospectively. Unenhanced T1-weighted gradient echo (T1wGRE) and T2-weighted turbo spin echo (T2wTSE) images were acquired followed by contrast-enhanced T1wGRE images during the dynamic, equilibrium, and delayed phases after the bolus injection of 0.05 mmol/kg gadobenate dimeglumine. An identical series of dynamic images was then acquired after the delayed scan following a second 0.05 mmol/kg bolus of gadobenate dimeglumine. Images were evaluated randomly in 2 sessions by 3 independent blinded readers. Evaluated images in the first session comprised the unenhanced images, the first or second set of dynamic images, and the delayed images. The second session included the unenhanced images, the dynamic images not yet evaluated in the first session, and the delayed images. The 2 reading sessions were compared for lesion characterization and diagnosis, and kappa (kappa) values for interobserver agreement were determined. Quantitative evaluation of lesion contrast enhancement was also performed.

RESULTS

The enhancement behavior in the second dynamic series was similar to that in the first series, although pre-enhancement of the normal liver resulted in reduced lesion-liver contrast-to-noise ratios and the visualization of some lesions only on arterial phase images. Typical imaging features for the lesions included in the study were visualized clearly in both series. Strong agreement (kappa=0.56-0.89; all evaluations) between the 2 images sets was noted by all readers for differentiation of benign from malignant lesions and for definition of specific diagnosis, and between readers for diagnoses established based on images acquired in the unenhanced and pre-enhanced liver.

CONCLUSION

Dynamic imaging in the hepatobiliary phase gives similar information as dynamic imaging of the unenhanced liver. This might prove advantageous for screening protocols involving same session imaging of primary extrahepatic tumors and liver.

Liver metastases: imaging considerations for protocol development with multislice CT (MSCT)

Conventional, single-slice helical computed tomography (SSCT) allowed for scanning the majority of the liver during the critical portal venous phase. This was often referred to as the ‘optimal temporal window’. The introduction of current day multislice CT (MSCT) now allows us to acquire images in a much shorter time and more precisely than ever before. This yields increased conspicuity between low attenuation lesions and the enhanced normal liver parenchyma and optimal imaging for the vast majority of hepatic hypovascular metastases. Most importantly, these scanners, when compared to conventional non-helical scanners, avoid impinging upon the ‘equilibrium’ phase when tumors can become isodense/invisible. MSCT also allows for true multiphase scanning during the arterial and late arterial phases for detection of hypervascular metastases. The MSCT imaging speed has increased significantly over the past years with the introduction of 32- and 64-detector systems and will continue to increase in the future volumetric CT. This provides a number of important gains that are discussed in detail.

Comparison of mangafodipir trisodium- and ferucarbotran-enhanced MRI for detection and characterization of hepatic metastases in colorectal cancer patients

OBJECTIVE

The purpose of our study was to evaluate the validity of mangafodipir trisodium-enhanced versus ferucarbotran-enhanced MRI in the detection and characterization of hepatic lesions in colorectal cancer patients.

MATERIALS AND METHODS

Forty-one patients who were known to have or suspected of having hepatic metastasis from colorectal carcinoma underwent mangafodipir trisodium- or ferucarbotran-enhanced MRI in block randomization methods. Two radiologists independently reviewed the MR images to determine the number of hepatic lesions and to characterize the lesions as malignant or benign. Each lesion was assessed according to its size (small, <or= 2 cm; large, > 2 cm in diameter) on both mangafodipir trisodium- or ferucarbotran-enhanced MRI. The data were correlated with the reference diagnosis: histopathology and intraoperative sonography (n = 16); intraoperative sonography (n = 4); and imaging and clinical diagnosis with follow-up (> 3 months; n = 21). The detection rates and diagnostic accuracies of hepatic lesions on both sets of MR images were assessed using Fisher's exact test.

RESULTS

Eighty-two hepatic lesions (53 metastatic and 29 benign) were identified in 41 patients. No significant differences were seen between mangafodipir trisodium- and ferucarbotran-enhanced MRI for detecting all hepatic lesions (p = 0.183), small hepatic lesions (p = 0.299), all metastases (p = 0.695), and small metastases (p = 0.689). The diagnostic accuracies of mangafodipir trisodium- and ferucarbotran-enhanced MRI showed no significant differences in all hepatic lesions (p = 0.624) and small hepatic lesions (p = 0.641).

CONCLUSION

Mangafodipir trisodium- and ferucarbotran-enhanced MRI are similar in hepatic lesion detection and characterization in colorectal cancer patients.

Liver Metastases on Serial Contrast-enhanced Multidetector Computed Tomography Examinations

OBJECTIVE

To verify the earliest detectability of liver metastases in patients who underwent serial multidetector computed tomography (MDCT) examinations.

METHODS

We selected 12 patients with known primary cancer who underwent 4 or more contrast-enhanced, 4-detector MDCTs. When metastases had been reported, an evaluation of the preceding MDCT was done to define whether the lesion was detectable, detectable only by minimal signs, undetectable, or detected but misdiagnosed as a benign lesion (MBL).

RESULTS

Eighty-eight lesions were analyzed. Evaluating the preceding examination, we defined detectable (n=8), detectable only by minimal signs (n=5), undetectable (n=74), and MBL (n=1). The group with minimal signs was composed of 4 small hypodense foci and 1 calcification. The MBL was a non-Hodgkin lesion first misdiagnosed as a hemangioma.

CONCLUSION

Approximately 15% of liver metastases were prospectively missed, 9% of them being retrospectively detectable, 6% being retrospectively visible as minimal signs, whereas only 1% of liver metastases were misdiagnosed as a benign lesion.

Doppler sonographic evaluation of hemodynamic changes in colorectal liver metastases relative to liver size

OBJECTIVE

The mechanisms of hemodynamic alterations in colorectal liver metastases are not clearly understood yet. Considering that an increase in liver size in patients with metastases could also result in an alteration in total liver flow, we aimed to analyze hemodynamic changes relative to the liver volume and to search for the possibility of any intrinsic factors affecting blood flow in patients with metastases.

METHODS

Twenty-eight patients with colorectal liver metastases and 20 control subjects with no liver disease were evaluated sonographically. All patients were examined prospectively by Doppler sonography and helical computed tomography. Hepatic hemodynamic parameters, including blood flow in the hepatic artery and portal vein, total blood flow to the liver, and Doppler perfusion index, were calculated, and values relative to liver volume were obtained. Hepatic perfusion changes in liver metastases were then compared with those in a control group.

RESULTS

The liver volume of the patients with liver metastases was greater than that of the control group (P=.003). Hepatic arterial blood flow rates were higher, whereas portal flow rates were lower, in patients with liver metastases compared with control subjects (P<.05). Total liver blood flow was not significantly different between the two groups. However, total blood flow relative to liver volume was significantly lower in the metastatic group (P<.001). Doppler perfusion index values in the patients with metastasis were significantly higher than in the control group (P=.000).

CONCLUSIONS

Our findings may support the hypothesis that a humoral mediator-induced portal venous flow reduction causes perfusion changes in liver metastases from colorectal disease. However, an additional intrinsic hepatic hemodynamic event should also be present. Doppler perfusion index measurements can provide additional information in the evaluation of patients with colorectal liver metastases.

Computed Tomography Imaging of Gastrointestinal Stromal Tumors With Pathology Correlation

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that typically arise in association with the muscularis propria of gastrointestinal (GI) tract wall. They occur most frequently in the stomach (60%) but also can occur in the small bowel (30%) or elsewhere, including the colon and rectum (5%) and esophagus (<5%). In addition, a GIST may occur as a primary tumor of the omentum, mesentery, or retroperitoneum. They account for 1%-3% of gastric neoplasms, 20% of small bowel tumors, and 0.2%-1% of colorectal tumors. These tumors arise pathologically from the wall of the GI tract and can be characterized as benign, borderline, or with low or high malignant potential based on the pathologic appearance. Computed tomography (CT) plays an important role for the diagnosis and staging of these neoplasms because it can identify the tumor and assess for local spread or distant metastases. This article reviews the role of CT in the detection and characterization of GISTs. The optimal CT technique for visualization of small bowel tumors is reviewed, and a variety of GISTs are illustrated. Pathologic correlation is also included.

MRI for Detection of Hepatocellular Carcinoma: Comparison of Mangafodipir Trisodium and Gadopentetate Dimeglumine Contrast Agents

OBJECTIVE

The purpose of our study was to compare the performance of mangafodipir trisodium (Mn-DPDP)-enhanced and dynamic gadopentetate dimeglumine-enhanced MRI for the detection of hepatocellular carcinoma.

MATERIALS AND METHODS

Forty-six patients with 96 hepatocellular carcinomas underwent Mn-DPDP- and gadopentetate dimeglumine-enhanced MRI. The MRI examination included unenhanced T2-weighted turbo spin-echo and T1-weighted 2D fast low-angle shot (FLASH) sequences and a 3D FLASH sequence after the administration of gadopentetate dimeglumine and Mn-DPDP. Two observers reviewed three sets of images: a set of gadopentetate dimeglumine-enhanced MR images, a set of Mn-DPDP-enhanced MR images, and a combination of the gadopentetate dimeglumine and Mn-DPDP sets. Using receiver operating characteristic (ROC) analysis, imaging sets were compared for diagnostic accuracy and sensitivity.

RESULTS

The area under the ROC curve (A(z)) was 0.942 for the gadopentetate dimeglumine-Mn-DPDP set, 0.932 for the gadopentetate dimeglumine set, and 0.877 for the Mn-DPDP set (p < 0.05). The mean sensitivity was greater for the gadopentetate dimeglumine set than for the Mn-DPDP set (87.5% vs 72.4%; p < 0.05). The false-negative rate of the Mn-DPDP set was statistically greater than that of the gadopentetate dimeglumine set (27.6% vs 12.5%). Most false-negative cases in the Mn-DPDP set were due to small (diameter < 2 cm), isoenhanced lesions.

CONCLUSION

Gadopentetate dimeglumine-enhanced MRI was superior to Mn-DPDP-enhanced MRI for the detection of hepatocellular carcinomas.

Recent advances in CT imaging of liver metastases

Multidetector computed tomography provides robust evaluation of the hepatic parenchyma. It plays a critical role in the detection of liver metastases and the assessment of treatment response to therapy. In this article, we discuss the role of multidetector computed tomography in the detection and characterization of hepatic metastases, and the value of image processing with volume rendering and maximum-intensity projection techniques in the accurate delineation of hepatic vascular anatomy and the segmental localization of lesions. This information is critical in the diagnosis and treatment of patients with metastatic disease and is essential in surgical and nonsurgical planning.

Focal hepatic lesions: contrast-enhancement patterns at pulse-inversion harmonic US using a microbubble contrast agent

Objective

To analyze the contrast-enhancement patterns obtained at pulse-inversion harmonic imaging (PIHI) of focal hepatic lesions, and to thus determine tumor vascularity and the acoustic emission effect.

Materials and Methods

We reviewed pulse-inversion images in 90 consecutive patients with focal hepatic lesions, namely hepatocellular carcinoma (HCC) (n=43), metastases (n=30), and hemangioma (n=17). Vascular and delayed phase images were obtained immediately and five minutes following the injection of a microbubble contrast agent. Tumoral vascularity at vascular phase imaging and the acoustic emission effect at delayed phase imaging were each classified as one of four patterns.

Results

Vascular phase images depicted internal vessels in 93% of HCCs, marginal vessels in 83% of metastases, and peripheral nodular enhancement in 71% of hemangiomas. Delayed phase images showed inhomogeneous enhancement in 86% of HCCs; hypoechoic, decreased enhancement in 93% of metastases; and hypoechoic and reversed echogenicity in 65% of hemangiomas. Vascular and delayed phase enhancement patterns were associated with a specificity of 91% or greater, and 92% or greater, respectively, and with positive predictive values of 71% or greater, and 85% or greater, respectively.

Conclusion

Contrast-enhancement patterns depicting tumoral vascularity and the acoustic emission effect at PIHI can help differentiate focal hepatic lesions.

Detection of hypovascular hepatic metastases at triple-phase helical CT: sensitivity of phases and comparison with surgical and histopathologic findings

PURPOSE

To compare the respective sensitivities of unenhanced, arterial-dominant, and portal-dominant phase helical computed tomography (CT) in the preoperative depiction of hypovascular hepatic metastases by using intraoperative ultrasonographic (US) and histopathologic findings as the standard of reference.

MATERIALS AND METHODS

In this prospective study, 32 patients with 59 surgically and histopathologically proved hypovascular hepatic metastases underwent triple-phase helical CT of the liver, which included unenhanced, arterial-dominant, and portal-dominant phase scanning. Images from each phase were separately analyzed by three readers, and disagreements were resolved with consensus readings. The findings on CT images were compared with intraoperative US and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each imaging phase. Statistical review of the lesion-by-lesion analysis was performed by using the Wilcoxon rank sum test.

RESULTS

Among 59 hepatic metastases, unenhanced, arterial-dominant, and portal-dominant phase helical CT imaging depicted 39 (66.1%; 95% CI: 53.3%, 76.8%), 44 (74.5%; 95% CI: 62.2%, 83.9%), and 54 (91.5%; 95% CI: 81.6%, 96.3%) metastases, respectively. Portal-dominant phase imaging depicted significantly more hypovascular hepatic metastases than did unenhanced (P <.001) or arterial-dominant (P <.01) phase imaging (Wilcoxon test).

CONCLUSION

Preoperative use of triple-phase helical CT in patients with hypovascular hepatic metastases may not be warranted. Portal-dominant phase helical CT imaging allows depiction of significantly more hypovascular hepatic metastases than does imaging during any of the other phases.

Détection de métastases hépatiques du cancer colorectal sous chimiothérapie

OBJECTIVE

To compare MRI of the liver with mangafodipir trisodium (MnDPDP) and computed tomography with intravenous contrast media in the follow-up of liver metastases in patient on chemotherapy for colorectal carcinoma.

MATERIALS AND METHODS

This was a prospective study with patients on chemotherapy for liver metastases from colorectal cancer. Patients underwent both contrast-enhanced helical CT using 2 cc/kg contrast at 3 cc/sec and mangafodipir trisodium-enhanced MR imaging at 1.5 T using 2-3 cc/min contrast at 5 micro mol/kg within a two week interval. Two experienced radiologists independently reviewed all scans in a blinded fashion and recorded image quality as well as presence and number of liver lesions. Statistical analysis was performed using the wilcoxon signed rank test.

RESULTS

All examinations were of good quality. A total of 71 lesions were detected at CT, with 69 lesions consistent with metastases and 2 lesions consistent with cysts. A total of 98 lesions were detected at MRI, with 97 consistent with metastases and 1 lesion consistent with a cyst. T1 weighted images with MnDPDP significantly detected two additional lesions compared to CT (p<0.05). No significant difference was demonstrated between T1 weighted images without MnDPDP and CT or between T2 weighted images and CT.

CONCLUSION

Magnetic resonance imaging with MnDPDP is significantly more sensitive than unenhanced MRI and helical CT for the follow-up of liver lesions.

Surgically staged focal liver lesions: accuracy and reproducibility of dual-phase helical CT for detection and characterization

PURPOSE

To assess the accuracy and reproducibility of dual-phase helical computed tomography (CT) in enabling preoperative detection and characterization of surgically staged focal liver lesions.

MATERIALS AND METHODS

Surgically and histopathologically proven liver lesions were evaluated by three experienced CT readers. These lesions were present in 77 patients who underwent dual-phase helical CT. Images were interpreted separately by the three blinded reviewers. Each lesion was graded on a nine-point scale of confidence, with 1 being definitely benign, 9 being definitely malignant, and 5 being indeterminate. The chi2 test was used to determine if the distribution of lesion classifications was different between readers.

RESULTS

There was a total of 237 lesions: 73 were benign and 164 were malignant. Sensitivity for lesion detection was 69%, 70%, and 71% for the three reviewers, respectively. Specificity was 91%, 86%, and 90%, and the area under the curve for the alternative-free response receiver operating characteristic curve was 0.84, 0.83, and 0.85, respectively. The difference in the distributions of lesion classification between the three reviewers was not statistically significant (P =.67) as determined by chi2 analysis.

CONCLUSION

Dual-phase CT has sensitivity of 69%-71% and high specificity (86%-91%) in enabling the detection and characterization of focal liver lesions. Interpretation is highly reproducible, as there is minimal variation between experienced reviewers.